Release v5.3.28

Closes gh-30670

(cherry picked from commit b9221656cc)

.gitignore

@@ -46,4 +46,6 @@ atlassian-ide-plugin.xml
 .gradletasknamecache
 
 # VS Code
-.vscode/
+.vscode/
+
+cached-antora-playbook.yml

.sdkmanrc

@@ -1,3 +1,3 @@
 # Enable auto-env through the sdkman_auto_env config
 # Add key=value pairs of SDKs to use below
-java=8.0.362-librca
+java=8.0.372-librca

build.gradle

@@ -28,8 +28,8 @@ configure(allprojects) { project ->
 	dependencyManagement {
 		imports {
 			mavenBom "com.fasterxml.jackson:jackson-bom:2.12.7"
-			mavenBom "io.netty:netty-bom:4.1.90.Final"
-			mavenBom "io.projectreactor:reactor-bom:2020.0.30"
+			mavenBom "io.netty:netty-bom:4.1.93.Final"
+			mavenBom "io.projectreactor:reactor-bom:2020.0.33"
 			mavenBom "io.r2dbc:r2dbc-bom:Arabba-SR13"
 			mavenBom "io.rsocket:rsocket-bom:1.1.3"
 			mavenBom "org.eclipse.jetty:jetty-bom:9.4.51.v20230217"
@@ -128,18 +128,18 @@ configure(allprojects) { project ->
 			dependency "org.webjars:webjars-locator-core:0.48"
 			dependency "org.webjars:underscorejs:1.8.3"
 
-			dependencySet(group: 'org.apache.tomcat', version: '9.0.73') {
+			dependencySet(group: 'org.apache.tomcat', version: '9.0.75') {
 				entry 'tomcat-util'
 				entry('tomcat-websocket') {
 					exclude group: "org.apache.tomcat", name: "tomcat-servlet-api"
 					exclude group: "org.apache.tomcat", name: "tomcat-websocket-api"
 				}
 			}
-			dependencySet(group: 'org.apache.tomcat.embed', version: '9.0.73') {
+			dependencySet(group: 'org.apache.tomcat.embed', version: '9.0.75') {
 				entry 'tomcat-embed-core'
 				entry 'tomcat-embed-websocket'
 			}
-			dependencySet(group: 'io.undertow', version: '2.2.23.Final') {
+			dependencySet(group: 'io.undertow', version: '2.2.24.Final') {
 				entry 'undertow-core'
 				entry('undertow-servlet') {
 					exclude group: "org.jboss.spec.javax.servlet", name: "jboss-servlet-api_4.0_spec"
@@ -238,7 +238,7 @@ configure(allprojects) { project ->
 			dependency "com.ibm.websphere:uow:6.0.2.17"
 			dependency "com.jamonapi:jamon:2.82"
 			dependency "joda-time:joda-time:2.10.13"
-			dependency "org.eclipse.persistence:org.eclipse.persistence.jpa:2.7.10"
+			dependency "org.eclipse.persistence:org.eclipse.persistence.jpa:2.7.12"
 			dependency "org.javamoney:moneta:1.3"
 
 			dependency "com.sun.activation:javax.activation:1.2.0"
@@ -340,7 +340,7 @@ configure([rootProject] + javaProjects) { project ->
 	}
 
 	checkstyle {
-		toolVersion = "10.9.1"
+		toolVersion = "10.9.3"
 		configDirectory.set(rootProject.file("src/checkstyle"))
 	}
 

ci/images/get-jdk-url.sh

@@ -3,10 +3,10 @@ set -e
 
 case "$1" in
 	java8)
-		 echo "https://github.com/bell-sw/Liberica/releases/download/8u345+1/bellsoft-jdk8u345+1-linux-amd64.tar.gz"
+		 echo "https://github.com/bell-sw/Liberica/releases/download/8u372+7/bellsoft-jdk8u372+7-linux-amd64.tar.gz"
 	;;
 	java17)
-		echo "https://github.com/bell-sw/Liberica/releases/download/17.0.4+8/bellsoft-jdk17.0.4+8-linux-amd64.tar.gz"
+		echo "https://github.com/bell-sw/Liberica/releases/download/17.0.7+7/bellsoft-jdk17.0.7+7-linux-amd64.tar.gz"
 	;;
 	*)
 		echo $"Unknown java version"

ci/pipeline.yml

@@ -64,12 +64,6 @@ resource_types:
     <<: *docker-resource-source
     repository: dpb587/github-status-resource
     tag: master
-- name: pull-request
-  type: registry-image
-  source:
-    <<: *docker-resource-source
-    repository: teliaoss/github-pr-resource
-    tag: v0.23.0
 - name: slack-notification
   type: registry-image
   source:
@@ -111,14 +105,6 @@ resources:
     username: ((artifactory-username))
     password: ((artifactory-password))
     build_name: ((build-name))
-- name: git-pull-request
-  type: pull-request
-  icon: source-pull
-  source:
-    access_token: ((github-ci-pull-request-token))
-    repository: ((github-repo-name))
-    base_branch: ((branch))
-    ignore_paths: ["ci/*"]
 - name: repo-status-build
   type: github-status-resource
   icon: eye-check-outline
@@ -259,37 +245,6 @@ jobs:
               <<: *slack-fail-params
     - put: repo-status-jdk17-build
       params: { state: "success", commit: "git-repo" }
-- name: build-pull-requests
-  serial: true
-  public: true
-  plan:
-    - get: ci-image
-    - get: git-repo
-      resource: git-pull-request
-      trigger: true
-      version: every
-    - do:
-      - put: git-pull-request
-        params:
-          path: git-repo
-          status: pending
-      - task: build-pr
-        image: ci-image
-        file: git-repo/ci/tasks/build-pr.yml
-        privileged: true
-        timeout: ((task-timeout))
-        params:
-          BRANCH: ((branch))
-      on_success:
-        put: git-pull-request
-        params:
-          path: git-repo
-          status: success
-      on_failure:
-        put: git-pull-request
-        params:
-          path: git-repo
-          status: failure
 - name: stage-milestone
   serial: true
   plan:
@@ -442,5 +397,3 @@ groups:
   jobs: ["stage-milestone", "stage-rc", "stage-release", "promote-milestone", "promote-rc", "promote-release", "create-github-release"]
 - name: "ci-images"
   jobs: ["build-ci-images"]
-- name: "pull-requests"
-  jobs: [ "build-pull-requests" ]

gradle.properties

@@ -1,4 +1,4 @@
-version=5.3.26
+version=5.3.28
 org.gradle.jvmargs=-Xmx2048m
 org.gradle.caching=true
 org.gradle.parallel=true

gradle/docs.gradle

@@ -3,7 +3,7 @@ configurations {
 }
 
 dependencies {
-	asciidoctorExt("io.spring.asciidoctor:spring-asciidoctor-extensions-block-switch:0.5.0")
+	asciidoctorExt("io.spring.asciidoctor:spring-asciidoctor-extensions-block-switch:0.6.1")
 }
 
 repositories {
@@ -73,9 +73,8 @@ pluginManager.withPlugin("kotlin") {
 }
 
 task downloadResources(type: Download) {
-	def version = "0.2.5"
-	src "https://repo.spring.io/release/io/spring/docresources/" +
-			"spring-doc-resources/$version/spring-doc-resources-${version}.zip"
+	src "https://repo.spring.io/artifactory/snapshot/io/spring/docresources/" +
+			"spring-doc-resources/0.2.6-SNAPSHOT/spring-doc-resources-0.2.6-20210308.231804-2.zip"
 	dest project.file("$buildDir/docs/spring-doc-resources.zip")
 	onlyIfModified true
 	useETag "all"

spring-aop/src/main/java/org/springframework/aop/aspectj/AspectJAdviceParameterNameDiscoverer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -38,6 +38,14 @@ import org.springframework.util.StringUtils;
  * for an advice method from the pointcut expression, returning, and throwing clauses.
  * If an unambiguous interpretation is not available, it returns {@code null}.
  *
+ * <h3>Algorithm Summary</h3>
+ * <p>If an unambiguous binding can be deduced, then it is.
+ * If the advice requirements cannot possibly be satisfied, then {@code null}
+ * is returned. By setting the {@link #setRaiseExceptions(boolean) raiseExceptions}
+ * property to {@code true}, descriptive exceptions will be thrown instead of
+ * returning {@code null} in the case that the parameter names cannot be discovered.
+ *
+ * <h3>Algorithm Details</h3>
  * <p>This class interprets arguments in the following way:
  * <ol>
  * <li>If the first parameter of the method is of type {@link JoinPoint}
@@ -65,15 +73,15 @@ import org.springframework.util.StringUtils;
  * zero we proceed to the next stage. If {@code a} &gt; 1 then an
  * {@code AmbiguousBindingException} is raised. If {@code a} == 1,
  * and there are no unbound arguments of type {@code Annotation+},
- * then an {@code IllegalArgumentException} is raised. if there is
+ * then an {@code IllegalArgumentException} is raised. If there is
  * exactly one such argument, then the corresponding parameter name is
  * assigned the value from the pointcut expression.</li>
- * <li>If a returningName has been set, and there are no unbound arguments
+ * <li>If a {@code returningName} has been set, and there are no unbound arguments
  * then an {@code IllegalArgumentException} is raised. If there is
  * more than one unbound argument then an
  * {@code AmbiguousBindingException} is raised. If there is exactly
  * one unbound argument then the corresponding parameter name is assigned
- * the value &lt;returningName&gt;.</li>
+ * the value of the {@code returningName}.</li>
  * <li>If there remain unbound arguments, then the pointcut expression is
  * examined once more for {@code this}, {@code target}, and
  * {@code args} pointcut expressions used in the binding form (binding
@@ -99,20 +107,12 @@ import org.springframework.util.StringUtils;
  * <p>The behavior on raising an {@code IllegalArgumentException} or
  * {@code AmbiguousBindingException} is configurable to allow this discoverer
  * to be used as part of a chain-of-responsibility. By default the condition will
- * be logged and the {@code getParameterNames(..)} method will simply return
+ * be logged and the {@link #getParameterNames(Method)} method will simply return
  * {@code null}. If the {@link #setRaiseExceptions(boolean) raiseExceptions}
  * property is set to {@code true}, the conditions will be thrown as
  * {@code IllegalArgumentException} and {@code AmbiguousBindingException},
  * respectively.
  *
- * <p>Was that perfectly clear? ;)
- *
- * <p>Short version: If an unambiguous binding can be deduced, then it is.
- * If the advice requirements cannot possibly be satisfied, then {@code null}
- * is returned. By setting the {@link #setRaiseExceptions(boolean) raiseExceptions}
- * property to {@code true}, descriptive exceptions will be thrown instead of
- * returning {@code null} in the case that the parameter names cannot be discovered.
- *
  * @author Adrian Colyer
  * @author Juergen Hoeller
  * @since 2.0
@@ -158,7 +158,7 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 
 	/** The pointcut expression associated with the advice, as a simple String. */
 	@Nullable
-	private String pointcutExpression;
+	private final String pointcutExpression;
 
 	private boolean raiseExceptions;
 
@@ -197,7 +197,7 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 
 	/**
 	 * If {@code afterReturning} advice binds the return value, the
-	 * returning variable name must be specified.
+	 * {@code returning} variable name must be specified.
 	 * @param returningName the name of the returning variable
 	 */
 	public void setReturningName(@Nullable String returningName) {
@@ -206,18 +206,17 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 
 	/**
 	 * If {@code afterThrowing} advice binds the thrown value, the
-	 * throwing variable name must be specified.
+	 * {@code throwing} variable name must be specified.
 	 * @param throwingName the name of the throwing variable
 	 */
 	public void setThrowingName(@Nullable String throwingName) {
 		this.throwingName = throwingName;
 	}
 
-
 	/**
 	 * Deduce the parameter names for an advice method.
-	 * <p>See the {@link AspectJAdviceParameterNameDiscoverer class level javadoc}
-	 * for this class for details of the algorithm used.
+	 * <p>See the {@link AspectJAdviceParameterNameDiscoverer class-level javadoc}
+	 * for this class for details on the algorithm used.
 	 * @param method the target {@link Method}
 	 * @return the parameter names
 	 */
@@ -316,13 +315,13 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 	}
 
 
-	private void bindParameterName(int index, String name) {
+	private void bindParameterName(int index, @Nullable String name) {
 		this.parameterNameBindings[index] = name;
 		this.numberOfRemainingUnboundArguments--;
 	}
 
 	/**
-	 * If the first parameter is of type JoinPoint or ProceedingJoinPoint,bind "thisJoinPoint" as
+	 * If the first parameter is of type JoinPoint or ProceedingJoinPoint, bind "thisJoinPoint" as
 	 * parameter name and return true, else return false.
 	 */
 	private boolean maybeBindThisJoinPoint() {
@@ -367,8 +366,8 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 		}
 
 		if (throwableIndex == -1) {
-			throw new IllegalStateException("Binding of throwing parameter '" + this.throwingName
-					+ "' could not be completed as no available arguments are a subtype of Throwable");
+			throw new IllegalStateException("Binding of throwing parameter '" + this.throwingName +
+					"' could not be completed as no available arguments are a subtype of Throwable");
 		}
 		else {
 			bindParameterName(throwableIndex, this.throwingName);
@@ -400,7 +399,6 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 		}
 	}
 
-
 	/**
 	 * Parse the string pointcut expression looking for:
 	 * &#64;this, &#64;target, &#64;args, &#64;within, &#64;withincode, &#64;annotation.
@@ -465,7 +463,7 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 		}
 	}
 
-	/*
+	/**
 	 * If the token starts meets Java identifier conventions, it's in.
 	 */
 	@Nullable
@@ -533,7 +531,6 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 			}
 		}
 
-
 		if (varNames.size() > 1) {
 			throw new AmbiguousBindingException("Found " + varNames.size() +
 					" candidate this(), target() or args() variables but only one unbound argument slot");
@@ -609,7 +606,7 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 		// else varNames.size must be 0 and we have nothing to bind.
 	}
 
-	/*
+	/**
 	 * We've found the start of a binding pointcut at the given index into the
 	 * token array. Now we need to extract the pointcut body and return it.
 	 */
@@ -709,7 +706,7 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 		return false;
 	}
 
-	/*
+	/**
 	 * Return {@code true} if the given argument type is a subclass
 	 * of the given supertype.
 	 */
@@ -737,7 +734,7 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 		return count;
 	}
 
-	/*
+	/**
 	 * Find the argument index with the given type, and bind the given
 	 * {@code varName} in that position.
 	 */

spring-aop/src/main/java/org/springframework/aop/framework/AdvisedSupport.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -521,6 +521,7 @@ public class AdvisedSupport extends ProxyConfig implements Advised {
 		copy.copyFrom(this);
 		copy.targetSource = EmptyTargetSource.forClass(getTargetClass(), getTargetSource().isStatic());
 		copy.advisorChainFactory = this.advisorChainFactory;
+		copy.methodCache = this.methodCache;
 		copy.interfaces = new ArrayList<>(this.interfaces);
 		copy.advisors = new ArrayList<>(this.advisors);
 		return copy;

spring-aop/src/main/java/org/springframework/aop/framework/CglibAopProxy.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -283,8 +283,8 @@ class CglibAopProxy implements AopProxy, Serializable {
 
 	private Callback[] getCallbacks(Class<?> rootClass) throws Exception {
 		// Parameters used for optimization choices...
-		boolean exposeProxy = this.advised.isExposeProxy();
 		boolean isFrozen = this.advised.isFrozen();
+		boolean exposeProxy = this.advised.isExposeProxy();
 		boolean isStatic = this.advised.getTargetSource().isStatic();
 
 		// Choose an "aop" interceptor (used for AOP calls).
@@ -899,9 +899,9 @@ class CglibAopProxy implements AopProxy, Serializable {
 			// Proxy is not yet available, but that shouldn't matter.
 			List<?> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
 			boolean haveAdvice = !chain.isEmpty();
+			boolean isFrozen = this.advised.isFrozen();
 			boolean exposeProxy = this.advised.isExposeProxy();
 			boolean isStatic = this.advised.getTargetSource().isStatic();
-			boolean isFrozen = this.advised.isFrozen();
 			if (haveAdvice || !isFrozen) {
 				// If exposing the proxy, then AOP_PROXY must be used.
 				if (exposeProxy) {
@@ -970,6 +970,9 @@ class CglibAopProxy implements AopProxy, Serializable {
 			if (this.advised.isExposeProxy() != otherAdvised.isExposeProxy()) {
 				return false;
 			}
+			if (this.advised.isOpaque() != otherAdvised.isOpaque()) {
+				return false;
+			}
 			if (this.advised.getTargetSource().isStatic() != otherAdvised.getTargetSource().isStatic()) {
 				return false;
 			}
@@ -1016,10 +1019,6 @@ class CglibAopProxy implements AopProxy, Serializable {
 				Advice advice = advisor.getAdvice();
 				hashCode = 13 * hashCode + advice.getClass().hashCode();
 			}
-			hashCode = 13 * hashCode + (this.advised.isFrozen() ? 1 : 0);
-			hashCode = 13 * hashCode + (this.advised.isExposeProxy() ? 1 : 0);
-			hashCode = 13 * hashCode + (this.advised.isOptimize() ? 1 : 0);
-			hashCode = 13 * hashCode + (this.advised.isOpaque() ? 1 : 0);
 			return hashCode;
 		}
 	}

spring-aop/src/main/java/org/springframework/aop/framework/JdkDynamicAopProxy.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -123,7 +123,33 @@ final class JdkDynamicAopProxy implements AopProxy, InvocationHandler, Serializa
 		if (logger.isTraceEnabled()) {
 			logger.trace("Creating JDK dynamic proxy: " + this.advised.getTargetSource());
 		}
-		return Proxy.newProxyInstance(classLoader, this.proxiedInterfaces, this);
+		return Proxy.newProxyInstance(determineClassLoader(classLoader), this.proxiedInterfaces, this);
+	}
+
+	/**
+	 * Determine whether the JDK bootstrap or platform loader has been suggested ->
+	 * use higher-level loader which can see Spring infrastructure classes instead.
+	 */
+	private ClassLoader determineClassLoader(@Nullable ClassLoader classLoader) {
+		if (classLoader == null) {
+			// JDK bootstrap loader -> use spring-aop ClassLoader instead.
+			return getClass().getClassLoader();
+		}
+		if (classLoader.getParent() == null) {
+			// Potentially the JDK platform loader on JDK 9+
+			ClassLoader aopClassLoader = getClass().getClassLoader();
+			ClassLoader aopParent = aopClassLoader.getParent();
+			while (aopParent != null) {
+				if (classLoader == aopParent) {
+					// Suggested ClassLoader is ancestor of spring-aop ClassLoader
+					// -> use spring-aop ClassLoader itself instead.
+					return aopClassLoader;
+				}
+				aopParent = aopParent.getParent();
+			}
+		}
+		// Regular case: use suggested ClassLoader as-is.
+		return classLoader;
 	}
 
 	/**

spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/target/AbstractBeanFactoryBasedTargetSourceCreator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -34,6 +34,7 @@ import org.springframework.beans.factory.config.ConfigurableBeanFactory;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.beans.factory.support.GenericBeanDefinition;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * Convenient superclass for
@@ -81,6 +82,11 @@ public abstract class AbstractBeanFactoryBasedTargetSourceCreator
 		return this.beanFactory;
 	}
 
+	private ConfigurableBeanFactory getConfigurableBeanFactory() {
+		Assert.state(this.beanFactory != null, "BeanFactory not set");
+		return this.beanFactory;
+	}
+
 
 	//---------------------------------------------------------------------
 	// Implementation of the TargetSourceCreator interface
@@ -104,7 +110,7 @@ public abstract class AbstractBeanFactoryBasedTargetSourceCreator
 		// We need to override just this bean definition, as it may reference other beans
 		// and we're happy to take the parent's definition for those.
 		// Always use prototype scope if demanded.
-		BeanDefinition bd = this.beanFactory.getMergedBeanDefinition(beanName);
+		BeanDefinition bd = getConfigurableBeanFactory().getMergedBeanDefinition(beanName);
 		GenericBeanDefinition bdCopy = new GenericBeanDefinition(bd);
 		if (isPrototypeBased()) {
 			bdCopy.setScope(BeanDefinition.SCOPE_PROTOTYPE);
@@ -126,7 +132,7 @@ public abstract class AbstractBeanFactoryBasedTargetSourceCreator
 	protected DefaultListableBeanFactory getInternalBeanFactoryForBean(String beanName) {
 		synchronized (this.internalBeanFactories) {
 			return this.internalBeanFactories.computeIfAbsent(beanName,
-					name -> buildInternalBeanFactory(this.beanFactory));
+					name -> buildInternalBeanFactory(getConfigurableBeanFactory()));
 		}
 	}
 

spring-aop/src/main/java/org/springframework/aop/target/AbstractBeanFactoryBasedTargetSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,8 @@ import org.apache.commons.logging.LogFactory;
 import org.springframework.aop.TargetSource;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 
 /**
@@ -57,15 +59,18 @@ public abstract class AbstractBeanFactoryBasedTargetSource implements TargetSour
 	protected final Log logger = LogFactory.getLog(getClass());
 
 	/** Name of the target bean we will create on each invocation. */
+	@Nullable
 	private String targetBeanName;
 
 	/** Class of the target. */
+	@Nullable
 	private volatile Class<?> targetClass;
 
 	/**
 	 * BeanFactory that owns this TargetSource. We need to hold onto this
 	 * reference so that we can create new prototype instances as necessary.
 	 */
+	@Nullable
 	private BeanFactory beanFactory;
 
 
@@ -86,6 +91,7 @@ public abstract class AbstractBeanFactoryBasedTargetSource implements TargetSour
 	 * Return the name of the target bean in the factory.
 	 */
 	public String getTargetBeanName() {
+		Assert.state(this.targetBeanName != null, "Target bean name not set");
 		return this.targetBeanName;
 	}
 
@@ -115,11 +121,13 @@ public abstract class AbstractBeanFactoryBasedTargetSource implements TargetSour
 	 * Return the owning BeanFactory.
 	 */
 	public BeanFactory getBeanFactory() {
+		Assert.state(this.beanFactory != null, "BeanFactory not set");
 		return this.beanFactory;
 	}
 
 
 	@Override
+	@Nullable
 	public Class<?> getTargetClass() {
 		Class<?> targetClass = this.targetClass;
 		if (targetClass != null) {
@@ -128,7 +136,7 @@ public abstract class AbstractBeanFactoryBasedTargetSource implements TargetSour
 		synchronized (this) {
 			// Full check within synchronization, entering the BeanFactory interaction algorithm only once...
 			targetClass = this.targetClass;
-			if (targetClass == null && this.beanFactory != null) {
+			if (targetClass == null && this.beanFactory != null && this.targetBeanName != null) {
 				// Determine type of the target bean.
 				targetClass = this.beanFactory.getType(this.targetBeanName);
 				if (targetClass == null) {
@@ -182,18 +190,16 @@ public abstract class AbstractBeanFactoryBasedTargetSource implements TargetSour
 
 	@Override
 	public int hashCode() {
-		int hashCode = getClass().hashCode();
-		hashCode = 13 * hashCode + ObjectUtils.nullSafeHashCode(this.beanFactory);
-		hashCode = 13 * hashCode + ObjectUtils.nullSafeHashCode(this.targetBeanName);
-		return hashCode;
+		return getClass().hashCode() * 13 + ObjectUtils.nullSafeHashCode(this.targetBeanName);
 	}
 
 	@Override
 	public String toString() {
 		StringBuilder sb = new StringBuilder(getClass().getSimpleName());
 		sb.append(" for target bean '").append(this.targetBeanName).append('\'');
-		if (this.targetClass != null) {
-			sb.append(" of type [").append(this.targetClass.getName()).append(']');
+		Class<?> targetClass = this.targetClass;
+		if (targetClass != null) {
+			sb.append(" of type [").append(targetClass.getName()).append(']');
 		}
 		return sb.toString();
 	}

spring-aop/src/main/java/org/springframework/aop/target/AbstractLazyCreationTargetSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -46,6 +46,7 @@ public abstract class AbstractLazyCreationTargetSource implements TargetSource {
 	protected final Log logger = LogFactory.getLog(getClass());
 
 	/** The lazily initialized target object. */
+	@Nullable
 	private Object lazyTarget;
 
 

spring-aop/src/main/java/org/springframework/aop/target/EmptyTargetSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -70,6 +70,7 @@ public final class EmptyTargetSource implements TargetSource, Serializable {
 	// Instance implementation
 	//---------------------------------------------------------------------
 
+	@Nullable
 	private final Class<?> targetClass;
 
 	private final boolean isStatic;

spring-aop/src/main/java/org/springframework/aop/target/HotSwappableTargetSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -95,8 +95,7 @@ public class HotSwappableTargetSource implements TargetSource, Serializable {
 
 
 	/**
-	 * Two HotSwappableTargetSources are equal if the current target
-	 * objects are equal.
+	 * Two HotSwappableTargetSources are equal if the current target objects are equal.
 	 */
 	@Override
 	public boolean equals(Object other) {

spring-aop/src/main/java/org/springframework/aop/target/SingletonTargetSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -82,14 +82,8 @@ public class SingletonTargetSource implements TargetSource, Serializable {
 	 */
 	@Override
 	public boolean equals(Object other) {
-		if (this == other) {
-			return true;
-		}
-		if (!(other instanceof SingletonTargetSource)) {
-			return false;
-		}
-		SingletonTargetSource otherTargetSource = (SingletonTargetSource) other;
-		return this.target.equals(otherTargetSource.target);
+		return (this == other || (other instanceof SingletonTargetSource &&
+				this.target.equals(((SingletonTargetSource) other).target)));
 	}
 
 	/**

spring-aop/src/main/java/org/springframework/aop/target/ThreadLocalTargetSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -58,7 +58,12 @@ public class ThreadLocalTargetSource extends AbstractPrototypeBasedTargetSource
 	 * is meant to be per thread per instance of the ThreadLocalTargetSource class.
 	 */
 	private final ThreadLocal<Object> targetInThread =
-			new NamedThreadLocal<>("Thread-local instance of bean '" + getTargetBeanName() + "'");
+			new NamedThreadLocal<Object>("Thread-local instance of bean") {
+				@Override
+				public String toString() {
+					return super.toString() + " '" + getTargetBeanName() + "'";
+				}
+			};
 
 	/**
 	 * Set of managed targets, enabling us to keep track of the targets we've created.

spring-aop/src/test/java/org/springframework/aop/framework/ProxyFactoryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,10 @@
 
 package org.springframework.aop.framework;
 
+import java.sql.SQLException;
+import java.sql.Savepoint;
 import java.util.ArrayList;
+import java.util.Date;
 import java.util.List;
 
 import javax.accessibility.Accessible;
@@ -380,6 +383,43 @@ public class ProxyFactoryTests {
 		assertThat(proxy.getName()).isEqualTo("tb");
 	}
 
+	@Test
+	public void testCharSequenceProxy() {
+		CharSequence target = "test";
+		ProxyFactory pf = new ProxyFactory(target);
+		ClassLoader cl = target.getClass().getClassLoader();
+		CharSequence proxy = (CharSequence) pf.getProxy(cl);
+		assertThat(proxy.toString()).isEqualTo(target);
+	}
+
+	@Test
+	public void testDateProxy() {
+		Date target = new Date();
+		ProxyFactory pf = new ProxyFactory(target);
+		pf.setProxyTargetClass(true);
+		ClassLoader cl = target.getClass().getClassLoader();
+		Date proxy = (Date) pf.getProxy(cl);
+		assertThat(proxy.getTime()).isEqualTo(target.getTime());
+	}
+
+	@Test
+	public void testJdbcSavepointProxy() throws SQLException {
+		Savepoint target = new Savepoint() {
+			@Override
+			public int getSavepointId() throws SQLException {
+				return 1;
+			}
+			@Override
+			public String getSavepointName() throws SQLException {
+				return "sp";
+			}
+		};
+		ProxyFactory pf = new ProxyFactory(target);
+		ClassLoader cl = Savepoint.class.getClassLoader();
+		Savepoint proxy = (Savepoint) pf.getProxy(cl);
+		assertThat(proxy.getSavepointName()).isEqualTo("sp");
+	}
+
 
 	@Order(2)
 	public static class A implements Runnable {
@@ -391,7 +431,7 @@ public class ProxyFactoryTests {
 
 
 	@Order(1)
-	public static class B implements Runnable{
+	public static class B implements Runnable {
 
 		@Override
 		public void run() {

spring-beans/src/main/java/org/springframework/beans/factory/BeanFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -136,7 +136,10 @@ public interface BeanFactory {
 	 * <p>Translates aliases back to the corresponding canonical bean name.
 	 * <p>Will ask the parent factory if the bean cannot be found in this factory instance.
 	 * @param name the name of the bean to retrieve
-	 * @return an instance of the bean
+	 * @return an instance of the bean.
+	 * Note that the return value will never be {@code null} but possibly a stub for
+	 * {@code null} returned from a factory method, to be checked via {@code equals(null)}.
+	 * Consider using {@link #getBeanProvider(Class)} for resolving optional dependencies.
 	 * @throws NoSuchBeanDefinitionException if there is no bean with the specified name
 	 * @throws BeansException if the bean could not be obtained
 	 */
@@ -152,7 +155,11 @@ public interface BeanFactory {
 	 * <p>Will ask the parent factory if the bean cannot be found in this factory instance.
 	 * @param name the name of the bean to retrieve
 	 * @param requiredType type the bean must match; can be an interface or superclass
-	 * @return an instance of the bean
+	 * @return an instance of the bean.
+	 * Note that the return value will never be {@code null}. In case of a stub for
+	 * {@code null} from a factory method having been resolved for the requested bean, a
+	 * {@code BeanNotOfRequiredTypeException} against the NullBean stub will be raised.
+	 * Consider using {@link #getBeanProvider(Class)} for resolving optional dependencies.
 	 * @throws NoSuchBeanDefinitionException if there is no such bean definition
 	 * @throws BeanNotOfRequiredTypeException if the bean is not of the required type
 	 * @throws BeansException if the bean could not be created

spring-beans/src/main/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -665,7 +665,7 @@ public class AutowiredAnnotationBeanPostProcessor implements SmartInstantiationA
 					if (value != null || this.required) {
 						cachedFieldValue = desc;
 						registerDependentBeans(beanName, autowiredBeanNames);
-						if (autowiredBeanNames.size() == 1) {
+						if (value != null && autowiredBeanNames.size() == 1) {
 							String autowiredBeanName = autowiredBeanNames.iterator().next();
 							if (beanFactory.containsBean(autowiredBeanName) &&
 									beanFactory.isTypeMatch(autowiredBeanName, field.getType())) {
@@ -778,7 +778,7 @@ public class AutowiredAnnotationBeanPostProcessor implements SmartInstantiationA
 							Class<?>[] paramTypes = method.getParameterTypes();
 							for (int i = 0; i < paramTypes.length; i++) {
 								String autowiredBeanName = it.next();
-								if (beanFactory.containsBean(autowiredBeanName) &&
+								if (arguments[i] != null && beanFactory.containsBean(autowiredBeanName) &&
 										beanFactory.isTypeMatch(autowiredBeanName, paramTypes[i])) {
 									cachedMethodArguments[i] = new ShortcutDependencyDescriptor(
 											descriptors[i], autowiredBeanName, paramTypes[i]);

spring-beans/src/main/java/org/springframework/beans/factory/support/DefaultSingletonBeanRegistry.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -102,7 +102,7 @@ public class DefaultSingletonBeanRegistry extends SimpleAliasRegistry implements
 	private boolean singletonsCurrentlyInDestruction = false;
 
 	/** Disposable bean instances: bean name to disposable instance. */
-	private final Map<String, Object> disposableBeans = new LinkedHashMap<>();
+	private final Map<String, DisposableBean> disposableBeans = new LinkedHashMap<>();
 
 	/** Map between containing bean names: bean name to Set of bean names that the bean contains. */
 	private final Map<String, Set<String>> containedBeanMap = new ConcurrentHashMap<>(16);
@@ -340,7 +340,7 @@ public class DefaultSingletonBeanRegistry extends SimpleAliasRegistry implements
 	 * (within the entire factory).
 	 * @param beanName the name of the bean
 	 */
-	public boolean isSingletonCurrentlyInCreation(String beanName) {
+	public boolean isSingletonCurrentlyInCreation(@Nullable String beanName) {
 		return this.singletonsCurrentlyInCreation.contains(beanName);
 	}
 
@@ -554,7 +554,7 @@ public class DefaultSingletonBeanRegistry extends SimpleAliasRegistry implements
 		// Destroy the corresponding DisposableBean instance.
 		DisposableBean disposableBean;
 		synchronized (this.disposableBeans) {
-			disposableBean = (DisposableBean) this.disposableBeans.remove(beanName);
+			disposableBean = this.disposableBeans.remove(beanName);
 		}
 		destroyBean(beanName, disposableBean);
 	}

spring-beans/src/main/java/org/springframework/beans/factory/support/DisposableBeanAdapter.java

@@ -68,8 +68,8 @@ class DisposableBeanAdapter implements DisposableBean, Runnable, Serializable {
 
 	private static final String SHUTDOWN_METHOD_NAME = "shutdown";
 
-	private static final Log logger = LogFactory.getLog(DisposableBeanAdapter.class);
 
+	private static final Log logger = LogFactory.getLog(DisposableBeanAdapter.class);
 
 	private final Object bean;
 

spring-beans/src/test/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -133,6 +133,26 @@ public class AutowiredAnnotationBeanPostProcessorTests {
 		assertThat(bean.getTestBean2()).isSameAs(tb);
 	}
 
+	@Test
+	public void testResourceInjectionWithNullBean() {
+		RootBeanDefinition bd = new RootBeanDefinition(NonPublicResourceInjectionBean.class);
+		bd.setScope(BeanDefinition.SCOPE_PROTOTYPE);
+		bf.registerBeanDefinition("annotatedBean", bd);
+		RootBeanDefinition tb = new RootBeanDefinition(NullFactoryMethods.class);
+		tb.setFactoryMethodName("createTestBean");
+		bf.registerBeanDefinition("testBean", tb);
+
+		NonPublicResourceInjectionBean bean = (NonPublicResourceInjectionBean) bf.getBean("annotatedBean");
+		assertThat(bean.getTestBean()).isNull();
+		assertThat(bean.getTestBean2()).isNull();
+		assertThat(bean.getTestBean3()).isNull();
+
+		bean = (NonPublicResourceInjectionBean) bf.getBean("annotatedBean");
+		assertThat(bean.getTestBean()).isNull();
+		assertThat(bean.getTestBean2()).isNull();
+		assertThat(bean.getTestBean3()).isNull();
+	}
+
 	@Test
 	public void testExtendedResourceInjection() {
 		RootBeanDefinition bd = new RootBeanDefinition(TypedExtendedResourceInjectionBean.class);

spring-context/src/main/java/org/springframework/cache/interceptor/NameMatchCacheOperationSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -47,7 +47,7 @@ public class NameMatchCacheOperationSource implements CacheOperationSource, Seri
 
 
 	/** Keys are method names; values are TransactionAttributes. */
-	private Map<String, Collection<CacheOperation>> nameMap = new LinkedHashMap<>();
+	private final Map<String, Collection<CacheOperation>> nameMap = new LinkedHashMap<>();
 
 
 	/**
@@ -117,8 +117,8 @@ public class NameMatchCacheOperationSource implements CacheOperationSource, Seri
 		if (!(other instanceof NameMatchCacheOperationSource)) {
 			return false;
 		}
-		NameMatchCacheOperationSource otherTas = (NameMatchCacheOperationSource) other;
-		return ObjectUtils.nullSafeEquals(this.nameMap, otherTas.nameMap);
+		NameMatchCacheOperationSource otherCos = (NameMatchCacheOperationSource) other;
+		return ObjectUtils.nullSafeEquals(this.nameMap, otherCos.nameMap);
 	}
 
 	@Override
@@ -130,4 +130,5 @@ public class NameMatchCacheOperationSource implements CacheOperationSource, Seri
 	public String toString() {
 		return getClass().getName() + ": " + this.nameMap;
 	}
+
 }

spring-context/src/main/java/org/springframework/context/event/ApplicationListenerMethodAdapter.java

@@ -274,7 +274,7 @@ public class ApplicationListenerMethodAdapter implements GenericApplicationListe
 					handleAsyncError(ex);
 				}
 				else if (event != null) {
-					publishEvent(event);
+					publishEvents(event);
 				}
 			});
 		}
@@ -468,6 +468,9 @@ public class ApplicationListenerMethodAdapter implements GenericApplicationListe
 	}
 
 
+	/**
+	 * Inner class to avoid a hard dependency on the Reactive Streams API at runtime.
+	 */
 	private class ReactiveResultHandler {
 
 		public boolean subscribeToPublisher(Object result) {
@@ -481,6 +484,9 @@ public class ApplicationListenerMethodAdapter implements GenericApplicationListe
 	}
 
 
+	/**
+	 * Reactive Streams Subscriber for publishing follow-up events.
+	 */
 	private class EventPublicationSubscriber implements Subscriber<Object> {
 
 		@Override

spring-context/src/main/java/org/springframework/context/support/AbstractApplicationContext.java

@@ -447,7 +447,7 @@ public abstract class AbstractApplicationContext extends DefaultResourceLoader
 
 	@Override
 	public void setApplicationStartup(ApplicationStartup applicationStartup) {
-		Assert.notNull(applicationStartup, "applicationStartup should not be null");
+		Assert.notNull(applicationStartup, "ApplicationStartup must not be null");
 		this.applicationStartup = applicationStartup;
 	}
 

spring-context/src/main/java/org/springframework/scheduling/annotation/Scheduled.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -117,9 +117,12 @@ public @interface Scheduled {
 	 * last invocation and the start of the next.
 	 * <p>The time unit is milliseconds by default but can be overridden via
 	 * {@link #timeUnit}.
+	 * <p>This attribute variant supports Spring-style "${...}" placeholders
+	 * as well as SpEL expressions.
 	 * @return the delay as a String value &mdash; for example, a placeholder
 	 * or a {@link java.time.Duration#parse java.time.Duration} compliant value
 	 * @since 3.2.2
+	 * @see #fixedDelay()
 	 */
 	String fixedDelayString() default "";
 
@@ -135,9 +138,12 @@ public @interface Scheduled {
 	 * Execute the annotated method with a fixed period between invocations.
 	 * <p>The time unit is milliseconds by default but can be overridden via
 	 * {@link #timeUnit}.
+	 * <p>This attribute variant supports Spring-style "${...}" placeholders
+	 * as well as SpEL expressions.
 	 * @return the period as a String value &mdash; for example, a placeholder
 	 * or a {@link java.time.Duration#parse java.time.Duration} compliant value
 	 * @since 3.2.2
+	 * @see #fixedRate()
 	 */
 	String fixedRateString() default "";
 
@@ -156,9 +162,12 @@ public @interface Scheduled {
 	 * {@link #fixedRate} or {@link #fixedDelay} task.
 	 * <p>The time unit is milliseconds by default but can be overridden via
 	 * {@link #timeUnit}.
+	 * <p>This attribute variant supports Spring-style "${...}" placeholders
+	 * as well as SpEL expressions.
 	 * @return the initial delay as a String value &mdash; for example, a placeholder
 	 * or a {@link java.time.Duration#parse java.time.Duration} compliant value
 	 * @since 3.2.2
+	 * @see #initialDelay()
 	 */
 	String initialDelayString() default "";
 

spring-context/src/main/java/org/springframework/scheduling/concurrent/ConcurrentTaskExecutor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -83,6 +83,9 @@ public class ConcurrentTaskExecutor implements AsyncListenableTaskExecutor, Sche
 
 	private TaskExecutorAdapter adaptedExecutor;
 
+	@Nullable
+	private TaskDecorator taskDecorator;
+
 
 	/**
 	 * Create a new ConcurrentTaskExecutor, using a single thread executor as default.
@@ -138,6 +141,7 @@ public class ConcurrentTaskExecutor implements AsyncListenableTaskExecutor, Sche
 	 * @since 4.3
 	 */
 	public final void setTaskDecorator(TaskDecorator taskDecorator) {
+		this.taskDecorator = taskDecorator;
 		this.adaptedExecutor.setTaskDecorator(taskDecorator);
 	}
 
@@ -174,11 +178,15 @@ public class ConcurrentTaskExecutor implements AsyncListenableTaskExecutor, Sche
 	}
 
 
-	private static TaskExecutorAdapter getAdaptedExecutor(Executor concurrentExecutor) {
+	private TaskExecutorAdapter getAdaptedExecutor(Executor concurrentExecutor) {
 		if (managedExecutorServiceClass != null && managedExecutorServiceClass.isInstance(concurrentExecutor)) {
 			return new ManagedTaskExecutorAdapter(concurrentExecutor);
 		}
-		return new TaskExecutorAdapter(concurrentExecutor);
+		TaskExecutorAdapter adapter = new TaskExecutorAdapter(concurrentExecutor);
+		if (this.taskDecorator != null) {
+			adapter.setTaskDecorator(this.taskDecorator);
+		}
+		return adapter;
 	}
 
 

spring-context/src/main/java/org/springframework/scheduling/concurrent/ConcurrentTaskScheduler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -100,7 +100,7 @@ public class ConcurrentTaskScheduler extends ConcurrentTaskExecutor implements T
 	 */
 	public ConcurrentTaskScheduler() {
 		super();
-		this.scheduledExecutor = initScheduledExecutor(null);
+		initScheduledExecutor(null);
 	}
 
 	/**
@@ -115,7 +115,7 @@ public class ConcurrentTaskScheduler extends ConcurrentTaskExecutor implements T
 	 */
 	public ConcurrentTaskScheduler(ScheduledExecutorService scheduledExecutor) {
 		super(scheduledExecutor);
-		this.scheduledExecutor = initScheduledExecutor(scheduledExecutor);
+		initScheduledExecutor(scheduledExecutor);
 	}
 
 	/**
@@ -131,11 +131,11 @@ public class ConcurrentTaskScheduler extends ConcurrentTaskExecutor implements T
 	 */
 	public ConcurrentTaskScheduler(Executor concurrentExecutor, ScheduledExecutorService scheduledExecutor) {
 		super(concurrentExecutor);
-		this.scheduledExecutor = initScheduledExecutor(scheduledExecutor);
+		initScheduledExecutor(scheduledExecutor);
 	}
 
 
-	private ScheduledExecutorService initScheduledExecutor(@Nullable ScheduledExecutorService scheduledExecutor) {
+	private void initScheduledExecutor(@Nullable ScheduledExecutorService scheduledExecutor) {
 		if (scheduledExecutor != null) {
 			this.scheduledExecutor = scheduledExecutor;
 			this.enterpriseConcurrentScheduler = (managedScheduledExecutorServiceClass != null &&
@@ -145,7 +145,6 @@ public class ConcurrentTaskScheduler extends ConcurrentTaskExecutor implements T
 			this.scheduledExecutor = Executors.newSingleThreadScheduledExecutor();
 			this.enterpriseConcurrentScheduler = false;
 		}
-		return this.scheduledExecutor;
 	}
 
 	/**

spring-context/src/main/java/org/springframework/scheduling/concurrent/ExecutorConfigurationSupport.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,7 +36,10 @@ import org.springframework.lang.Nullable;
  * Base class for setting up a {@link java.util.concurrent.ExecutorService}
  * (typically a {@link java.util.concurrent.ThreadPoolExecutor} or
  * {@link java.util.concurrent.ScheduledThreadPoolExecutor}).
- * Defines common configuration settings and common lifecycle handling.
+ *
+ * <p>Defines common configuration settings and common lifecycle handling,
+ * inheriting thread customization options (name, priority, etc) from
+ * {@link org.springframework.util.CustomizableThreadCreator}.
  *
  * @author Juergen Hoeller
  * @since 3.0
@@ -199,8 +202,7 @@ public abstract class ExecutorConfigurationSupport extends CustomizableThreadFac
 
 
 	/**
-	 * Calls {@code shutdown} when the BeanFactory destroys
-	 * the task executor instance.
+	 * Calls {@code shutdown} when the BeanFactory destroys the executor instance.
 	 * @see #shutdown()
 	 */
 	@Override

spring-context/src/main/java/org/springframework/validation/FieldError.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -125,7 +125,7 @@ public class FieldError extends ObjectError {
 	@Override
 	public String toString() {
 		return "Field error in object '" + getObjectName() + "' on field '" + this.field +
-				"': rejected value [" + ObjectUtils.nullSafeToString(this.rejectedValue) + "]; " +
+				"': rejected value [" + ObjectUtils.nullSafeConciseToString(this.rejectedValue) + "]; " +
 				resolvableToString();
 	}
 

spring-context/src/test/java/org/springframework/aop/framework/CglibProxyTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,6 +28,7 @@ import org.springframework.aop.MethodMatcher;
 import org.springframework.aop.Pointcut;
 import org.springframework.aop.support.AopUtils;
 import org.springframework.aop.support.DefaultPointcutAdvisor;
+import org.springframework.aop.support.annotation.AnnotationMatchingPointcut;
 import org.springframework.aop.testfixture.advice.CountingBeforeAdvice;
 import org.springframework.aop.testfixture.interceptor.NopInterceptor;
 import org.springframework.beans.testfixture.beans.ITestBean;
@@ -35,6 +36,8 @@ import org.springframework.beans.testfixture.beans.TestBean;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextException;
 import org.springframework.context.support.ClassPathXmlApplicationContext;
+import org.springframework.lang.NonNull;
+import org.springframework.lang.Nullable;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
@@ -87,8 +90,7 @@ public class CglibProxyTests extends AbstractAopProxyTests implements Serializab
 		AdvisedSupport pc = new AdvisedSupport(ITestBean.class);
 		pc.addAdvice(new NopInterceptor());
 		AopProxy aop = createAopProxy(pc);
-		assertThatExceptionOfType(AopConfigException.class).isThrownBy(
-				aop::getProxy);
+		assertThatExceptionOfType(AopConfigException.class).isThrownBy(aop::getProxy);
 	}
 
 	@Test
@@ -136,8 +138,8 @@ public class CglibProxyTests extends AbstractAopProxyTests implements Serializab
 
 		Object proxy = aop.getProxy();
 		assertThat(AopUtils.isCglibProxy(proxy)).isTrue();
-		assertThat(proxy instanceof ITestBean).isTrue();
-		assertThat(proxy instanceof TestBean).isTrue();
+		assertThat(proxy).isInstanceOf(ITestBean.class);
+		assertThat(proxy).isInstanceOf(TestBean.class);
 
 		TestBean tb = (TestBean) proxy;
 		assertThat(tb.getAge()).isEqualTo(32);
@@ -304,6 +306,8 @@ public class CglibProxyTests extends AbstractAopProxyTests implements Serializab
 		CglibAopProxy cglib = new CglibAopProxy(as);
 
 		ITestBean proxy1 = (ITestBean) cglib.getProxy();
+		ITestBean proxy1a = (ITestBean) cglib.getProxy();
+		assertThat(proxy1a.getClass()).isSameAs(proxy1.getClass());
 
 		mockTargetSource.setTarget(proxy1);
 		as = new AdvisedSupport(new Class<?>[]{});
@@ -312,7 +316,40 @@ public class CglibProxyTests extends AbstractAopProxyTests implements Serializab
 		cglib = new CglibAopProxy(as);
 
 		ITestBean proxy2 = (ITestBean) cglib.getProxy();
-		assertThat(proxy2 instanceof Serializable).isTrue();
+		assertThat(proxy2).isInstanceOf(Serializable.class);
+		assertThat(proxy2.getClass()).isNotSameAs(proxy1.getClass());
+
+		ITestBean proxy2a = (ITestBean) cglib.getProxy();
+		assertThat(proxy2a).isInstanceOf(Serializable.class);
+		assertThat(proxy2a.getClass()).isSameAs(proxy2.getClass());
+
+		mockTargetSource.setTarget(proxy1);
+		as = new AdvisedSupport(new Class<?>[]{});
+		as.setTargetSource(mockTargetSource);
+		as.addAdvisor(new DefaultPointcutAdvisor(new AnnotationMatchingPointcut(Nullable.class), new NopInterceptor()));
+		cglib = new CglibAopProxy(as);
+
+		ITestBean proxy3 = (ITestBean) cglib.getProxy();
+		assertThat(proxy3).isInstanceOf(Serializable.class);
+		assertThat(proxy3.getClass()).isNotSameAs(proxy2.getClass());
+
+		ITestBean proxy3a = (ITestBean) cglib.getProxy();
+		assertThat(proxy3a).isInstanceOf(Serializable.class);
+		assertThat(proxy3a.getClass()).isSameAs(proxy3.getClass());
+
+		mockTargetSource.setTarget(proxy1);
+		as = new AdvisedSupport(new Class<?>[]{});
+		as.setTargetSource(mockTargetSource);
+		as.addAdvisor(new DefaultPointcutAdvisor(new AnnotationMatchingPointcut(NonNull.class), new NopInterceptor()));
+		cglib = new CglibAopProxy(as);
+
+		ITestBean proxy4 = (ITestBean) cglib.getProxy();
+		assertThat(proxy4).isInstanceOf(Serializable.class);
+		assertThat(proxy4.getClass()).isNotSameAs(proxy3.getClass());
+
+		ITestBean proxy4a = (ITestBean) cglib.getProxy();
+		assertThat(proxy4a).isInstanceOf(Serializable.class);
+		assertThat(proxy4a.getClass()).isSameAs(proxy4.getClass());
 	}
 
 	@Test
@@ -331,7 +368,7 @@ public class CglibProxyTests extends AbstractAopProxyTests implements Serializab
 			proxy.doTest();
 		}
 		catch (Exception ex) {
-			assertThat(ex instanceof ApplicationContextException).as("Invalid exception class").isTrue();
+			assertThat(ex).as("Invalid exception class").isInstanceOf(ApplicationContextException.class);
 		}
 
 		assertThat(proxy.isCatchInvoked()).as("Catch was not invoked").isTrue();

spring-context/src/test/java/org/springframework/context/annotation/configuration/ImportTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,6 +41,7 @@ class ImportTests {
 
 	private DefaultListableBeanFactory processConfigurationClasses(Class<?>... classes) {
 		DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
+		beanFactory.setAllowBeanDefinitionOverriding(false);
 		for (Class<?> clazz : classes) {
 			beanFactory.registerBeanDefinition(clazz.getSimpleName(), new RootBeanDefinition(clazz));
 		}
@@ -56,9 +57,10 @@ class ImportTests {
 		for (Class<?> clazz : classes) {
 			beanFactory.getBean(clazz);
 		}
-
 	}
 
+	// ------------------------------------------------------------------------
+
 	@Test
 	void testProcessImportsWithAsm() {
 		int configClasses = 2;
@@ -158,6 +160,13 @@ class ImportTests {
 		assertBeanDefinitionCount(configClasses + beansInClasses, FirstLevel.class);
 	}
 
+	@Test
+	void testImportAnnotationWithThreeLevelRecursionAndDoubleImport() {
+		int configClasses = 5;
+		int beansInClasses = 5;
+		assertBeanDefinitionCount(configClasses + beansInClasses, FirstLevel.class, FirstLevelPlus.class);
+	}
+
 	// ------------------------------------------------------------------------
 
 	@Test
@@ -167,7 +176,6 @@ class ImportTests {
 		assertBeanDefinitionCount((configClasses + beansInClasses), WithMultipleArgumentsToImportAnnotation.class);
 	}
 
-
 	@Test
 	void testImportAnnotationWithMultipleArgumentsResultingInOverriddenBeanDefinition() {
 		DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
@@ -245,6 +253,11 @@ class ImportTests {
 		}
 	}
 
+	@Configuration
+	@Import(ThirdLevel.class)
+	static class FirstLevelPlus {
+	}
+
 	@Configuration
 	@Import({ThirdLevel.class, InitBean.class})
 	static class SecondLevel {

spring-context/src/test/java/org/springframework/format/datetime/DateFormattingTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -133,7 +133,7 @@ public class DateFormattingTests {
 		assertThat(exception)
 			.hasMessageContaining("for property 'styleDate'")
 			.hasCauseInstanceOf(ConversionFailedException.class).cause()
-				.hasMessageContaining("for value '99/01/01'")
+				.hasMessageContaining("for value [99/01/01]")
 				.hasCauseInstanceOf(IllegalArgumentException.class).cause()
 					.hasMessageContaining("Parse attempt failed for value [99/01/01]")
 					.hasCauseInstanceOf(ParseException.class).cause()
@@ -353,7 +353,7 @@ public class DateFormattingTests {
 			assertThat(fieldError.unwrap(TypeMismatchException.class))
 				.hasMessageContaining("for property 'patternDateWithFallbackPatterns'")
 				.hasCauseInstanceOf(ConversionFailedException.class).cause()
-					.hasMessageContaining("for value '210302'")
+					.hasMessageContaining("for value [210302]")
 					.hasCauseInstanceOf(IllegalArgumentException.class).cause()
 						.hasMessageContaining("Parse attempt failed for value [210302]")
 						.hasCauseInstanceOf(ParseException.class).cause()

spring-context/src/test/java/org/springframework/format/datetime/standard/DateTimeFormattingTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -333,7 +333,7 @@ class DateTimeFormattingTests {
 		assertThat(fieldError.unwrap(TypeMismatchException.class))
 			.hasMessageContaining("for property 'isoLocalDate'")
 			.hasCauseInstanceOf(ConversionFailedException.class).cause()
-				.hasMessageContaining("for value '2009-31-10'")
+				.hasMessageContaining("for value [2009-31-10]")
 				.hasCauseInstanceOf(IllegalArgumentException.class).cause()
 					.hasMessageContaining("Parse attempt failed for value [2009-31-10]")
 					.hasCauseInstanceOf(DateTimeParseException.class).cause()
@@ -540,7 +540,7 @@ class DateTimeFormattingTests {
 			assertThat(fieldError.unwrap(TypeMismatchException.class))
 				.hasMessageContaining("for property 'patternLocalDateWithFallbackPatterns'")
 				.hasCauseInstanceOf(ConversionFailedException.class).cause()
-					.hasMessageContaining("for value '210302'")
+					.hasMessageContaining("for value [210302]")
 					.hasCauseInstanceOf(IllegalArgumentException.class).cause()
 						.hasMessageContaining("Parse attempt failed for value [210302]")
 						.hasCauseInstanceOf(DateTimeParseException.class).cause()

spring-context/src/test/java/org/springframework/scheduling/concurrent/ConcurrentTaskExecutorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,7 @@
 
 package org.springframework.scheduling.concurrent;
 
+import java.util.concurrent.Executor;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.RunnableFuture;
 import java.util.concurrent.ThreadPoolExecutor;
@@ -26,6 +27,8 @@ import org.junit.jupiter.api.Test;
 
 import org.springframework.core.task.AsyncListenableTaskExecutor;
 import org.springframework.core.task.NoOpRunnable;
+import org.springframework.core.task.TaskDecorator;
+import org.springframework.util.Assert;
 
 import static org.assertj.core.api.Assertions.assertThatCode;
 
@@ -69,10 +72,40 @@ class ConcurrentTaskExecutorTests extends AbstractSchedulingTaskExecutorTests {
 	}
 
 	@Test
-	void passingNullExecutorToSetterResultsInDefaultTaskExecutorBeingUsed() {
+	void earlySetConcurrentExecutorCallRespectsConfiguredTaskDecorator() {
 		ConcurrentTaskExecutor executor = new ConcurrentTaskExecutor();
-		executor.setConcurrentExecutor(null);
+		executor.setConcurrentExecutor(new DecoratedExecutor());
+		executor.setTaskDecorator(new RunnableDecorator());
 		assertThatCode(() -> executor.execute(new NoOpRunnable())).doesNotThrowAnyException();
 	}
 
+	@Test
+	void lateSetConcurrentExecutorCallRespectsConfiguredTaskDecorator() {
+		ConcurrentTaskExecutor executor = new ConcurrentTaskExecutor();
+		executor.setTaskDecorator(new RunnableDecorator());
+		executor.setConcurrentExecutor(new DecoratedExecutor());
+		assertThatCode(() -> executor.execute(new NoOpRunnable())).doesNotThrowAnyException();
+	}
+
+
+	private static class DecoratedRunnable implements Runnable {
+		@Override
+		public void run() {
+		}
+	}
+
+	private static class RunnableDecorator implements TaskDecorator {
+		@Override
+		public Runnable decorate(Runnable runnable) {
+			return new DecoratedRunnable();
+		}
+	}
+
+	private static class DecoratedExecutor implements Executor {
+		@Override
+		public void execute(Runnable command) {
+			Assert.state(command instanceof DecoratedRunnable, "TaskDecorator not applied");
+		}
+	}
+
 }

spring-core/src/main/java/org/springframework/core/CollectionFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -68,6 +68,7 @@ public final class CollectionFactory {
 		approximableCollectionTypes.add(SortedSet.class);
 		approximableCollectionTypes.add(NavigableSet.class);
 		approximableMapTypes.add(Map.class);
+		approximableMapTypes.add(MultiValueMap.class);
 		approximableMapTypes.add(SortedMap.class);
 		approximableMapTypes.add(NavigableMap.class);
 
@@ -80,6 +81,7 @@ public final class CollectionFactory {
 		approximableCollectionTypes.add(EnumSet.class);
 		approximableMapTypes.add(HashMap.class);
 		approximableMapTypes.add(LinkedHashMap.class);
+		approximableMapTypes.add(LinkedMultiValueMap.class);
 		approximableMapTypes.add(TreeMap.class);
 		approximableMapTypes.add(EnumMap.class);
 	}
@@ -121,13 +123,7 @@ public final class CollectionFactory {
 	 */
 	@SuppressWarnings({"rawtypes", "unchecked", "cast"})
 	public static <E> Collection<E> createApproximateCollection(@Nullable Object collection, int capacity) {
-		if (collection instanceof LinkedList) {
-			return new LinkedList<>();
-		}
-		else if (collection instanceof List) {
-			return new ArrayList<>(capacity);
-		}
-		else if (collection instanceof EnumSet) {
+		if (collection instanceof EnumSet) {
 			// Cast is necessary for compilation in Eclipse 4.4.1.
 			Collection<E> enumSet = (Collection<E>) EnumSet.copyOf((EnumSet) collection);
 			enumSet.clear();
@@ -136,6 +132,12 @@ public final class CollectionFactory {
 		else if (collection instanceof SortedSet) {
 			return new TreeSet<>(((SortedSet<E>) collection).comparator());
 		}
+		if (collection instanceof LinkedList) {
+			return new LinkedList<>();
+		}
+		else if (collection instanceof List) {
+			return new ArrayList<>(capacity);
+		}
 		else {
 			return new LinkedHashSet<>(capacity);
 		}
@@ -181,7 +183,7 @@ public final class CollectionFactory {
 	@SuppressWarnings({"unchecked", "cast"})
 	public static <E> Collection<E> createCollection(Class<?> collectionType, @Nullable Class<?> elementType, int capacity) {
 		Assert.notNull(collectionType, "Collection type must not be null");
-		if (LinkedHashSet.class == collectionType || HashSet.class == collectionType ||
+		if (LinkedHashSet.class == collectionType ||
 				Set.class == collectionType || Collection.class == collectionType) {
 			return new LinkedHashSet<>(capacity);
 		}
@@ -191,8 +193,8 @@ public final class CollectionFactory {
 		else if (LinkedList.class == collectionType) {
 			return new LinkedList<>();
 		}
-		else if (TreeSet.class == collectionType || NavigableSet.class == collectionType
-				|| SortedSet.class == collectionType) {
+		else if (TreeSet.class == collectionType || NavigableSet.class == collectionType ||
+				SortedSet.class == collectionType) {
 			return new TreeSet<>();
 		}
 		else if (EnumSet.class.isAssignableFrom(collectionType)) {
@@ -200,6 +202,9 @@ public final class CollectionFactory {
 			// Cast is necessary for compilation in Eclipse 4.4.1.
 			return (Collection<E>) EnumSet.noneOf(asEnumType(elementType));
 		}
+		else if (HashSet.class == collectionType) {
+			return new HashSet<>(capacity);
+		}
 		else {
 			if (collectionType.isInterface() || !Collection.class.isAssignableFrom(collectionType)) {
 				throw new IllegalArgumentException("Unsupported Collection type: " + collectionType.getName());
@@ -251,6 +256,9 @@ public final class CollectionFactory {
 		else if (map instanceof SortedMap) {
 			return new TreeMap<>(((SortedMap<K, V>) map).comparator());
 		}
+		else if (map instanceof MultiValueMap) {
+			return new LinkedMultiValueMap(capacity);
+		}
 		else {
 			return new LinkedHashMap<>(capacity);
 		}
@@ -297,26 +305,24 @@ public final class CollectionFactory {
 	@SuppressWarnings({"rawtypes", "unchecked"})
 	public static <K, V> Map<K, V> createMap(Class<?> mapType, @Nullable Class<?> keyType, int capacity) {
 		Assert.notNull(mapType, "Map type must not be null");
-		if (mapType.isInterface()) {
-			if (Map.class == mapType) {
-				return new LinkedHashMap<>(capacity);
-			}
-			else if (SortedMap.class == mapType || NavigableMap.class == mapType) {
-				return new TreeMap<>();
-			}
-			else if (MultiValueMap.class == mapType) {
-				return new LinkedMultiValueMap();
-			}
-			else {
-				throw new IllegalArgumentException("Unsupported Map interface: " + mapType.getName());
-			}
+		if (LinkedHashMap.class == mapType || Map.class == mapType) {
+			return new LinkedHashMap<>(capacity);
+		}
+		else if (LinkedMultiValueMap.class == mapType || MultiValueMap.class == mapType) {
+			return new LinkedMultiValueMap();
+		}
+		else if (TreeMap.class == mapType || SortedMap.class == mapType || NavigableMap.class == mapType) {
+			return new TreeMap<>();
 		}
 		else if (EnumMap.class == mapType) {
 			Assert.notNull(keyType, "Cannot create EnumMap for unknown key type");
 			return new EnumMap(asEnumType(keyType));
 		}
+		else if (HashMap.class == mapType) {
+			return new HashMap<>(capacity);
+		}
 		else {
-			if (!Map.class.isAssignableFrom(mapType)) {
+			if (mapType.isInterface() || !Map.class.isAssignableFrom(mapType)) {
 				throw new IllegalArgumentException("Unsupported Map type: " + mapType.getName());
 			}
 			try {

spring-core/src/main/java/org/springframework/core/MethodParameter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -781,6 +781,7 @@ public class MethodParameter {
 		return new MethodParameter(this);
 	}
 
+
 	/**
 	 * Create a new MethodParameter for the given method or constructor.
 	 * <p>This is a convenience factory method for scenarios where a

spring-core/src/main/java/org/springframework/core/convert/ConversionFailedException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -49,7 +49,7 @@ public class ConversionFailedException extends ConversionException {
 			@Nullable Object value, Throwable cause) {
 
 		super("Failed to convert from type [" + sourceType + "] to type [" + targetType +
-				"] for value '" + ObjectUtils.nullSafeToString(value) + "'", cause);
+				"] for value [" + ObjectUtils.nullSafeConciseToString(value) + "]", cause);
 		this.sourceType = sourceType;
 		this.targetType = targetType;
 		this.value = value;

spring-core/src/main/java/org/springframework/core/env/Environment.java

@@ -57,6 +57,8 @@ package org.springframework.core.env;
  * of property sources prior to application context {@code refresh()}.
  *
  * @author Chris Beams
+ * @author Phillip Webb
+ * @author Sam Brannen
  * @since 3.1
  * @see PropertyResolver
  * @see EnvironmentCapable
@@ -95,25 +97,56 @@ public interface Environment extends PropertyResolver {
 	String[] getDefaultProfiles();
 
 	/**
-	 * Return whether one or more of the given profiles is active or, in the case of no
-	 * explicit active profiles, whether one or more of the given profiles is included in
-	 * the set of default profiles. If a profile begins with '!' the logic is inverted,
-	 * i.e. the method will return {@code true} if the given profile is <em>not</em> active.
-	 * For example, {@code env.acceptsProfiles("p1", "!p2")} will return {@code true} if
-	 * profile 'p1' is active or 'p2' is not active.
-	 * @throws IllegalArgumentException if called with zero arguments
-	 * or if any profile is {@code null}, empty, or whitespace only
+	 * Determine whether one or more of the given profiles is active &mdash; or
+	 * in the case of no explicit {@linkplain #getActiveProfiles() active profiles},
+	 * whether one or more of the given profiles is included in the set of
+	 * {@linkplain #getDefaultProfiles() default profiles}.
+	 * <p>If a profile begins with '!' the logic is inverted, meaning this method
+	 * will return {@code true} if the given profile is <em>not</em> active. For
+	 * example, {@code env.acceptsProfiles("p1", "!p2")} will return {@code true}
+	 * if profile 'p1' is active or 'p2' is not active.
+	 * @throws IllegalArgumentException if called with a {@code null} array, an
+	 * empty array, zero arguments or if any profile is {@code null}, empty, or
+	 * whitespace only
 	 * @see #getActiveProfiles
 	 * @see #getDefaultProfiles
+	 * @see #matchesProfiles(String...)
 	 * @see #acceptsProfiles(Profiles)
-	 * @deprecated as of 5.1 in favor of {@link #acceptsProfiles(Profiles)}
+	 * @deprecated as of 5.1 in favor of {@link #acceptsProfiles(Profiles)} or
+	 * {@link #matchesProfiles(String...)}
 	 */
 	@Deprecated
 	boolean acceptsProfiles(String... profiles);
 
 	/**
-	 * Return whether the {@linkplain #getActiveProfiles() active profiles}
-	 * match the given {@link Profiles} predicate.
+	 * Determine whether one of the given profile expressions matches the
+	 * {@linkplain #getActiveProfiles() active profiles} &mdash; or in the case
+	 * of no explicit active profiles, whether one of the given profile expressions
+	 * matches the {@linkplain #getDefaultProfiles() default profiles}.
+	 * <p>Profile expressions allow for complex, boolean profile logic to be
+	 * expressed &mdash; for example {@code "p1 & p2"}, {@code "(p1 & p2) | p3"},
+	 * etc. See {@link Profiles#of(String...)} for details on the supported
+	 * expression syntax.
+	 * <p>This method is a convenient shortcut for
+	 * {@code env.acceptsProfiles(Profiles.of(profileExpressions))}.
+	 * @since 5.3.28
+	 * @see Profiles#of(String...)
+	 * @see #acceptsProfiles(Profiles)
+	 */
+	default boolean matchesProfiles(String... profileExpressions) {
+		return acceptsProfiles(Profiles.of(profileExpressions));
+	}
+
+	/**
+	 * Determine whether the given {@link Profiles} predicate matches the
+	 * {@linkplain #getActiveProfiles() active profiles} &mdash; or in the case
+	 * of no explicit active profiles, whether the given {@code Profiles} predicate
+	 * matches the {@linkplain #getDefaultProfiles() default profiles}.
+	 * <p>If you wish provide profile expressions directly as strings, use
+	 * {@link #matchesProfiles(String...)} instead.
+	 * @since 5.1
+	 * @see #matchesProfiles(String...)
+	 * @see Profiles#of(String...)
 	 */
 	boolean acceptsProfiles(Profiles profiles);
 

spring-core/src/main/java/org/springframework/core/env/Profiles.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,32 +43,32 @@ public interface Profiles {
 
 	/**
 	 * Create a new {@link Profiles} instance that checks for matches against
-	 * the given <em>profile strings</em>.
+	 * the given <em>profile expressions</em>.
 	 * <p>The returned instance will {@linkplain Profiles#matches(Predicate) match}
-	 * if any one of the given profile strings matches.
-	 * <p>A profile string may contain a simple profile name (for example
-	 * {@code "production"}) or a profile expression. A profile expression allows
+	 * if any one of the given profile expressions matches.
+	 * <p>A profile expression may contain a simple profile name (for example
+	 * {@code "production"}) or a compound expression. A compound expression allows
 	 * for more complicated profile logic to be expressed, for example
 	 * {@code "production & cloud"}.
 	 * <p>The following operators are supported in profile expressions.
 	 * <ul>
-	 * <li>{@code !} - A logical <em>NOT</em> of the profile or profile expression</li>
-	 * <li>{@code &} - A logical <em>AND</em> of the profiles or profile expressions</li>
-	 * <li>{@code |} - A logical <em>OR</em> of the profiles or profile expressions</li>
+	 * <li>{@code !} - A logical <em>NOT</em> of the profile name or compound expression</li>
+	 * <li>{@code &} - A logical <em>AND</em> of the profile names or compound expressions</li>
+	 * <li>{@code |} - A logical <em>OR</em> of the profile names or compound expressions</li>
 	 * </ul>
 	 * <p>Please note that the {@code &} and {@code |} operators may not be mixed
-	 * without using parentheses. For example {@code "a & b | c"} is not a valid
-	 * expression; it must be expressed as {@code "(a & b) | c"} or
+	 * without using parentheses. For example, {@code "a & b | c"} is not a valid
+	 * expression: it must be expressed as {@code "(a & b) | c"} or
 	 * {@code "a & (b | c)"}.
 	 * <p>As of Spring Framework 5.1.17, two {@code Profiles} instances returned
 	 * by this method are considered equivalent to each other (in terms of
 	 * {@code equals()} and {@code hashCode()} semantics) if they are created
-	 * with identical <em>profile strings</em>.
-	 * @param profiles the <em>profile strings</em> to include
+	 * with identical <em>profile expressions</em>.
+	 * @param profileExpressions the <em>profile expressions</em> to include
 	 * @return a new {@link Profiles} instance
 	 */
-	static Profiles of(String... profiles) {
-		return ProfilesParser.parse(profiles);
+	static Profiles of(String... profileExpressions) {
+		return ProfilesParser.parse(profileExpressions);
 	}
 
 }

spring-core/src/main/java/org/springframework/core/env/ProfilesParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,7 +43,7 @@ final class ProfilesParser {
 
 
 	static Profiles parse(String... expressions) {
-		Assert.notEmpty(expressions, "Must specify at least one profile");
+		Assert.notEmpty(expressions, "Must specify at least one profile expression");
 		Profiles[] parsed = new Profiles[expressions.length];
 		for (int i = 0; i < expressions.length; i++) {
 			parsed[i] = parseExpression(expressions[i]);
@@ -71,8 +71,8 @@ final class ProfilesParser {
 			}
 			switch (token) {
 				case "(":
-					Profiles contents = parseTokens(expression, tokens, Context.BRACKET);
-					if (context == Context.INVERT) {
+					Profiles contents = parseTokens(expression, tokens, Context.PARENTHESIS);
+					if (context == Context.NEGATE) {
 						return contents;
 					}
 					elements.add(contents);
@@ -86,11 +86,11 @@ final class ProfilesParser {
 					operator = Operator.OR;
 					break;
 				case "!":
-					elements.add(not(parseTokens(expression, tokens, Context.INVERT)));
+					elements.add(not(parseTokens(expression, tokens, Context.NEGATE)));
 					break;
 				case ")":
 					Profiles merged = merge(expression, elements, operator);
-					if (context == Context.BRACKET) {
+					if (context == Context.PARENTHESIS) {
 						return merged;
 					}
 					elements.clear();
@@ -99,7 +99,7 @@ final class ProfilesParser {
 					break;
 				default:
 					Profiles value = equals(token);
-					if (context == Context.INVERT) {
+					if (context == Context.NEGATE) {
 						return value;
 					}
 					elements.add(value);
@@ -137,15 +137,14 @@ final class ProfilesParser {
 		return activeProfile -> activeProfile.test(profile);
 	}
 
-	private static Predicate<Profiles> isMatch(Predicate<String> activeProfile) {
-		return profiles -> profiles.matches(activeProfile);
+	private static Predicate<Profiles> isMatch(Predicate<String> activeProfiles) {
+		return profiles -> profiles.matches(activeProfiles);
 	}
 
 
-	private enum Operator {AND, OR}
+	private enum Operator { AND, OR }
 
-
-	private enum Context {NONE, INVERT, BRACKET}
+	private enum Context { NONE, NEGATE, PARENTHESIS }
 
 
 	private static class ParsedProfiles implements Profiles {

spring-core/src/main/java/org/springframework/core/log/LogFormatUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,6 +23,7 @@ import org.apache.commons.logging.Log;
 
 import org.springframework.lang.Nullable;
 import org.springframework.util.ObjectUtils;
+import org.springframework.util.StringUtils;
 
 /**
  * Utility methods for formatting and logging messages.
@@ -78,7 +79,7 @@ public abstract class LogFormatUtils {
 			result = ObjectUtils.nullSafeToString(ex);
 		}
 		if (maxLength != -1) {
-			result = (result.length() > maxLength ? result.substring(0, maxLength) + " (truncated)..." : result);
+			result = StringUtils.truncate(result, maxLength);
 		}
 		if (replaceNewlinesAndControlCharacters) {
 			result = NEWLINE_PATTERN.matcher(result).replaceAll("<EOL>");

spring-core/src/main/java/org/springframework/core/serializer/DefaultDeserializer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -50,6 +50,7 @@ public class DefaultDeserializer implements Deserializer<Object> {
 	/**
 	 * Create a {@code DefaultDeserializer} for using an {@link ObjectInputStream}
 	 * with the given {@code ClassLoader}.
+	 * @param classLoader the ClassLoader to use
 	 * @since 4.2.1
 	 * @see ConfigurableObjectInputStream#ConfigurableObjectInputStream(InputStream, ClassLoader)
 	 */

spring-core/src/main/java/org/springframework/core/serializer/support/DeserializingConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@ import java.io.ByteArrayInputStream;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.core.serializer.DefaultDeserializer;
 import org.springframework.core.serializer.Deserializer;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -50,10 +51,11 @@ public class DeserializingConverter implements Converter<byte[], Object> {
 	/**
 	 * Create a {@code DeserializingConverter} for using an {@link java.io.ObjectInputStream}
 	 * with the given {@code ClassLoader}.
+	 * @param classLoader the ClassLoader to use
 	 * @since 4.2.1
 	 * @see DefaultDeserializer#DefaultDeserializer(ClassLoader)
 	 */
-	public DeserializingConverter(ClassLoader classLoader) {
+	public DeserializingConverter(@Nullable ClassLoader classLoader) {
 		this.deserializer = new DefaultDeserializer(classLoader);
 	}
 

spring-core/src/main/java/org/springframework/util/FileSystemUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -68,10 +68,10 @@ public abstract class FileSystemUtils {
 	}
 
 	/**
-	 * Delete the supplied {@link File} — for directories,
+	 * Delete the supplied {@link Path} — for directories,
 	 * recursively delete any nested directories or files as well.
-	 * @param root the root {@code File} to delete
-	 * @return {@code true} if the {@code File} existed and was deleted,
+	 * @param root the root {@code Path} to delete
+	 * @return {@code true} if the {@code Path} existed and was deleted,
 	 * or {@code false} if it did not exist
 	 * @throws IOException in the case of I/O errors
 	 * @since 5.0

spring-core/src/main/java/org/springframework/util/ObjectUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,11 +17,17 @@
 package org.springframework.util;
 
 import java.lang.reflect.Array;
+import java.net.URI;
+import java.net.URL;
+import java.time.temporal.Temporal;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Date;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
 import java.util.StringJoiner;
+import java.util.UUID;
 
 import org.springframework.lang.Nullable;
 
@@ -653,6 +659,7 @@ public abstract class ObjectUtils {
 	 * Returns a {@code "null"} String if {@code obj} is {@code null}.
 	 * @param obj the object to build a String representation for
 	 * @return a String representation of {@code obj}
+	 * @see #nullSafeConciseToString(Object)
 	 */
 	public static String nullSafeToString(@Nullable Object obj) {
 		if (obj == null) {
@@ -908,4 +915,70 @@ public abstract class ObjectUtils {
 		return stringJoiner.toString();
 	}
 
+	/**
+	 * Generate a null-safe, concise string representation of the supplied object
+	 * as described below.
+	 * <p>Favor this method over {@link #nullSafeToString(Object)} when you need
+	 * the length of the generated string to be limited.
+	 * <p>Returns:
+	 * <ul>
+	 * <li>{@code "null"} if {@code obj} is {@code null}</li>
+	 * <li>{@linkplain Class#getName() Class name} if {@code obj} is a {@link Class}</li>
+	 * <li>Potentially {@linkplain StringUtils#truncate(CharSequence) truncated string}
+	 * if {@code obj} is a {@link String} or {@link CharSequence}</li>
+	 * <li>Potentially {@linkplain StringUtils#truncate(CharSequence) truncated string}
+	 * if {@code obj} is a <em>simple value type</em> whose {@code toString()} method
+	 * returns a non-null value.</li>
+	 * <li>Otherwise, a string representation of the object's type name concatenated
+	 * with {@code @} and a hex string form of the object's identity hash code</li>
+	 * </ul>
+	 * <p>In the context of this method, a <em>simple value type</em> is any of the following:
+	 * a primitive wrapper (excluding {@code Void}), an {@code Enum}, a {@code Number},
+	 * a {@code Date}, a {@code Temporal}, a {@code UUID}, a {@code URI}, a {@code URL},
+	 * or a {@code Locale}.
+	 * @param obj the object to build a string representation for
+	 * @return a concise string representation of the supplied object
+	 * @since 5.3.27
+	 * @see #nullSafeToString(Object)
+	 * @see StringUtils#truncate(CharSequence)
+	 */
+	public static String nullSafeConciseToString(@Nullable Object obj) {
+		if (obj == null) {
+			return "null";
+		}
+		if (obj instanceof Class<?>) {
+			return ((Class<?>) obj).getName();
+		}
+		if (obj instanceof CharSequence) {
+			return StringUtils.truncate((CharSequence) obj);
+		}
+		Class<?> type = obj.getClass();
+		if (isSimpleValueType(type)) {
+			String str = obj.toString();
+			if (str != null) {
+				return StringUtils.truncate(str);
+			}
+		}
+		return type.getTypeName() + "@" + getIdentityHexString(obj);
+	}
+
+	/**
+	 * Derived from {@link org.springframework.beans.BeanUtils#isSimpleValueType}.
+	 * As of 5.3.28, considering {@code UUID} in addition to the bean-level check.
+	 */
+	private static boolean isSimpleValueType(Class<?> type) {
+		return (Void.class != type && void.class != type &&
+				(ClassUtils.isPrimitiveOrWrapper(type) ||
+				Enum.class.isAssignableFrom(type) ||
+				CharSequence.class.isAssignableFrom(type) ||
+				Number.class.isAssignableFrom(type) ||
+				Date.class.isAssignableFrom(type) ||
+				Temporal.class.isAssignableFrom(type) ||
+				UUID.class == type ||
+				URI.class == type ||
+				URL.class == type ||
+				Locale.class == type ||
+				Class.class == type));
+	}
+
 }

spring-core/src/main/java/org/springframework/util/StringUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -75,6 +75,10 @@ public abstract class StringUtils {
 
 	private static final char EXTENSION_SEPARATOR = '.';
 
+	private static final int DEFAULT_TRUNCATION_THRESHOLD = 100;
+
+	private static final String TRUNCATION_SUFFIX = " (truncated)...";
+
 
 	//---------------------------------------------------------------------
 	// General convenience methods for working with Strings
@@ -1388,4 +1392,40 @@ public abstract class StringUtils {
 		return arrayToDelimitedString(arr, ",");
 	}
 
+	/**
+	 * Truncate the supplied {@link CharSequence}.
+	 * <p>Delegates to {@link #truncate(CharSequence, int)}, supplying {@code 100}
+	 * as the threshold.
+	 * @param charSequence the {@code CharSequence} to truncate
+	 * @return a truncated string, or a string representation of the original
+	 * {@code CharSequence} if its length does not exceed the threshold
+	 * @since 5.3.27
+	 */
+	public static String truncate(CharSequence charSequence) {
+		return truncate(charSequence, DEFAULT_TRUNCATION_THRESHOLD);
+	}
+
+	/**
+	 * Truncate the supplied {@link CharSequence}.
+	 * <p>If the length of the {@code CharSequence} is greater than the threshold,
+	 * this method returns a {@linkplain CharSequence#subSequence(int, int)
+	 * subsequence} of the {@code CharSequence} (up to the threshold) appended
+	 * with the suffix {@code " (truncated)..."}. Otherwise, this method returns
+	 * {@code charSequence.toString()}.
+	 * @param charSequence the {@code CharSequence} to truncate
+	 * @param threshold the maximum length after which to truncate; must be a
+	 * positive number
+	 * @return a truncated string, or a string representation of the original
+	 * {@code CharSequence} if its length does not exceed the threshold
+	 * @since 5.3.27
+	 */
+	public static String truncate(CharSequence charSequence, int threshold) {
+		Assert.isTrue(threshold > 0,
+				() -> "Truncation threshold must be a positive number: " + threshold);
+		if (charSequence.length() > threshold) {
+			return charSequence.subSequence(0, threshold) + TRUNCATION_SUFFIX;
+		}
+		return charSequence.toString();
+	}
+
 }

spring-core/src/test/java/org/springframework/core/CollectionFactoryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -209,21 +209,23 @@ class CollectionFactoryTests {
 	@Test
 	void createsCollectionsCorrectly() {
 		// interfaces
-		assertThat(createCollection(List.class, 0)).isInstanceOf(ArrayList.class);
-		assertThat(createCollection(Set.class, 0)).isInstanceOf(LinkedHashSet.class);
-		assertThat(createCollection(Collection.class, 0)).isInstanceOf(LinkedHashSet.class);
-		assertThat(createCollection(SortedSet.class, 0)).isInstanceOf(TreeSet.class);
-		assertThat(createCollection(NavigableSet.class, 0)).isInstanceOf(TreeSet.class);
-
-		assertThat(createCollection(List.class, String.class, 0)).isInstanceOf(ArrayList.class);
-		assertThat(createCollection(Set.class, String.class, 0)).isInstanceOf(LinkedHashSet.class);
-		assertThat(createCollection(Collection.class, String.class, 0)).isInstanceOf(LinkedHashSet.class);
-		assertThat(createCollection(SortedSet.class, String.class, 0)).isInstanceOf(TreeSet.class);
-		assertThat(createCollection(NavigableSet.class, String.class, 0)).isInstanceOf(TreeSet.class);
+		testCollection(List.class, ArrayList.class);
+		testCollection(Set.class, LinkedHashSet.class);
+		testCollection(Collection.class, LinkedHashSet.class);
+		testCollection(SortedSet.class, TreeSet.class);
+		testCollection(NavigableSet.class, TreeSet.class);
 
 		// concrete types
-		assertThat(createCollection(HashSet.class, 0)).isInstanceOf(HashSet.class);
-		assertThat(createCollection(HashSet.class, String.class, 0)).isInstanceOf(HashSet.class);
+		testCollection(ArrayList.class, ArrayList.class);
+		testCollection(HashSet.class, HashSet.class);
+		testCollection(LinkedHashSet.class, LinkedHashSet.class);
+		testCollection(TreeSet.class, TreeSet.class);
+	}
+
+	private void testCollection(Class<?> collectionType, Class<?> resultType) {
+		assertThat(CollectionFactory.isApproximableCollectionType(collectionType)).isTrue();
+		assertThat(createCollection(collectionType, 0)).isExactlyInstanceOf(resultType);
+		assertThat(createCollection(collectionType, String.class, 0)).isExactlyInstanceOf(resultType);
 	}
 
 	@Test
@@ -258,20 +260,22 @@ class CollectionFactoryTests {
 	@Test
 	void createsMapsCorrectly() {
 		// interfaces
-		assertThat(createMap(Map.class, 0)).isInstanceOf(LinkedHashMap.class);
-		assertThat(createMap(SortedMap.class, 0)).isInstanceOf(TreeMap.class);
-		assertThat(createMap(NavigableMap.class, 0)).isInstanceOf(TreeMap.class);
-		assertThat(createMap(MultiValueMap.class, 0)).isInstanceOf(LinkedMultiValueMap.class);
-
-		assertThat(createMap(Map.class, String.class, 0)).isInstanceOf(LinkedHashMap.class);
-		assertThat(createMap(SortedMap.class, String.class, 0)).isInstanceOf(TreeMap.class);
-		assertThat(createMap(NavigableMap.class, String.class, 0)).isInstanceOf(TreeMap.class);
-		assertThat(createMap(MultiValueMap.class, String.class, 0)).isInstanceOf(LinkedMultiValueMap.class);
+		testMap(Map.class, LinkedHashMap.class);
+		testMap(SortedMap.class, TreeMap.class);
+		testMap(NavigableMap.class, TreeMap.class);
+		testMap(MultiValueMap.class, LinkedMultiValueMap.class);
 
 		// concrete types
-		assertThat(createMap(HashMap.class, 0)).isInstanceOf(HashMap.class);
+		testMap(HashMap.class, HashMap.class);
+		testMap(LinkedHashMap.class, LinkedHashMap.class);
+		testMap(TreeMap.class, TreeMap.class);
+		testMap(LinkedMultiValueMap.class, LinkedMultiValueMap.class);
+	}
 
-		assertThat(createMap(HashMap.class, String.class, 0)).isInstanceOf(HashMap.class);
+	private void testMap(Class<?> mapType, Class<?> resultType) {
+		assertThat(CollectionFactory.isApproximableMapType(mapType)).isTrue();
+		assertThat(createMap(mapType, 0)).isExactlyInstanceOf(resultType);
+		assertThat(createMap(mapType, String.class, 0)).isExactlyInstanceOf(resultType);
 	}
 
 	@Test

spring-core/src/test/java/org/springframework/core/env/ProfilesTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -40,30 +40,30 @@ class ProfilesTests {
 
 	@Test
 	void ofWhenNullThrowsException() {
-		assertThatIllegalArgumentException().isThrownBy(() ->
-				Profiles.of((String[]) null))
-			.withMessageContaining("Must specify at least one profile");
+		assertThatIllegalArgumentException()
+			.isThrownBy(() -> Profiles.of((String[]) null))
+			.withMessage("Must specify at least one profile expression");
 	}
 
 	@Test
 	void ofWhenEmptyThrowsException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(Profiles::of)
-			.withMessageContaining("Must specify at least one profile");
+			.withMessage("Must specify at least one profile expression");
 	}
 
 	@Test
 	void ofNullElement() {
-		assertThatIllegalArgumentException().isThrownBy(() ->
-				Profiles.of((String) null))
-			.withMessageContaining("must contain text");
+		assertThatIllegalArgumentException()
+			.isThrownBy(() -> Profiles.of((String) null))
+			.withMessage("Invalid profile expression [null]: must contain text");
 	}
 
 	@Test
 	void ofEmptyElement() {
-		assertThatIllegalArgumentException().isThrownBy(() ->
-				Profiles.of("  "))
-			.withMessageContaining("must contain text");
+		assertThatIllegalArgumentException()
+			.isThrownBy(() -> Profiles.of("  "))
+			.withMessage("Invalid profile expression [  ]: must contain text");
 	}
 
 	@Test
@@ -356,7 +356,7 @@ class ProfilesTests {
 	private static void assertMalformed(Supplier<Profiles> supplier) {
 		assertThatIllegalArgumentException()
 			.isThrownBy(supplier::get)
-			.withMessageContaining("Malformed");
+			.withMessageStartingWith("Malformed profile expression");
 	}
 
 	private static Predicate<String> activeProfiles(String... profiles) {

spring-core/src/test/java/org/springframework/core/env/StandardEnvironmentTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,9 +18,9 @@ package org.springframework.core.env;
 
 import java.security.AccessControlException;
 import java.security.Permission;
-import java.util.Arrays;
 import java.util.Map;
 
+import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.core.SpringProperties;
@@ -40,8 +40,7 @@ import static org.springframework.core.env.AbstractEnvironment.RESERVED_DEFAULT_
  * @author Juergen Hoeller
  * @author Sam Brannen
  */
-@SuppressWarnings("deprecation")
-public class StandardEnvironmentTests {
+class StandardEnvironmentTests {
 
 	private static final String ALLOWED_PROPERTY_NAME = "theanswer";
 	private static final String ALLOWED_PROPERTY_VALUE = "42";
@@ -81,8 +80,8 @@ public class StandardEnvironmentTests {
 		assertThat(parent.getProperty("parentKey")).isEqualTo("parentVal");
 		assertThat(parent.getProperty("bothKey")).isEqualTo("parentBothVal");
 
-		assertThat(child.getActiveProfiles()).isEqualTo(new String[]{"c1","c2"});
-		assertThat(parent.getActiveProfiles()).isEqualTo(new String[]{"p1","p2"});
+		assertThat(child.getActiveProfiles()).containsExactly("c1", "c2");
+		assertThat(parent.getActiveProfiles()).containsExactly("p1", "p2");
 
 		child.merge(parent);
 
@@ -94,8 +93,8 @@ public class StandardEnvironmentTests {
 		assertThat(parent.getProperty("parentKey")).isEqualTo("parentVal");
 		assertThat(parent.getProperty("bothKey")).isEqualTo("parentBothVal");
 
-		assertThat(child.getActiveProfiles()).isEqualTo(new String[]{"c1","c2","p1","p2"});
-		assertThat(parent.getActiveProfiles()).isEqualTo(new String[]{"p1","p2"});
+		assertThat(child.getActiveProfiles()).containsExactly("c1", "c2", "p1", "p2");
+		assertThat(parent.getActiveProfiles()).containsExactly("p1", "p2");
 	}
 
 	@Test
@@ -121,16 +120,14 @@ public class StandardEnvironmentTests {
 
 	@Test
 	void defaultProfilesContainsDefaultProfileByDefault() {
-		assertThat(environment.getDefaultProfiles().length).isEqualTo(1);
-		assertThat(environment.getDefaultProfiles()[0]).isEqualTo("default");
+		assertThat(environment.getDefaultProfiles()).containsExactly("default");
 	}
 
 	@Test
 	void setActiveProfiles() {
 		environment.setActiveProfiles("local", "embedded");
 		String[] activeProfiles = environment.getActiveProfiles();
-		assertThat(activeProfiles).contains("local", "embedded");
-		assertThat(activeProfiles.length).isEqualTo(2);
+		assertThat(activeProfiles).containsExactly("local", "embedded");
 	}
 
 	@Test
@@ -177,15 +174,12 @@ public class StandardEnvironmentTests {
 	void addActiveProfile() {
 		assertThat(environment.getActiveProfiles().length).isEqualTo(0);
 		environment.setActiveProfiles("local", "embedded");
-		assertThat(environment.getActiveProfiles()).contains("local", "embedded");
-		assertThat(environment.getActiveProfiles().length).isEqualTo(2);
+		assertThat(environment.getActiveProfiles()).containsExactly("local", "embedded");
 		environment.addActiveProfile("p1");
-		assertThat(environment.getActiveProfiles()).contains("p1");
-		assertThat(environment.getActiveProfiles().length).isEqualTo(3);
+		assertThat(environment.getActiveProfiles()).containsExactly("local", "embedded", "p1");
 		environment.addActiveProfile("p2");
 		environment.addActiveProfile("p3");
-		assertThat(environment.getActiveProfiles()).contains("p2", "p3");
-		assertThat(environment.getActiveProfiles().length).isEqualTo(5);
+		assertThat(environment.getActiveProfiles()).containsExactly("local", "embedded", "p1", "p2", "p3");
 	}
 
 	@Test
@@ -195,24 +189,17 @@ public class StandardEnvironmentTests {
 		env.getPropertySources().addFirst(new MockPropertySource().withProperty(ACTIVE_PROFILES_PROPERTY_NAME, "p1"));
 		assertThat(env.getProperty(ACTIVE_PROFILES_PROPERTY_NAME)).isEqualTo("p1");
 		env.addActiveProfile("p2");
-		assertThat(env.getActiveProfiles()).contains("p1", "p2");
+		assertThat(env.getActiveProfiles()).containsExactly("p1", "p2");
 	}
 
 	@Test
 	void reservedDefaultProfile() {
-		assertThat(environment.getDefaultProfiles()).isEqualTo(new String[]{RESERVED_DEFAULT_PROFILE_NAME});
-		System.setProperty(DEFAULT_PROFILES_PROPERTY_NAME, "d0");
-		assertThat(environment.getDefaultProfiles()).isEqualTo(new String[]{"d0"});
-		environment.setDefaultProfiles("d1", "d2");
-		assertThat(environment.getDefaultProfiles()).isEqualTo(new String[]{"d1","d2"});
-		System.clearProperty(DEFAULT_PROFILES_PROPERTY_NAME);
-	}
-
-	@Test
-	void defaultProfileWithCircularPlaceholder() {
+		assertThat(environment.getDefaultProfiles()).containsExactly(RESERVED_DEFAULT_PROFILE_NAME);
 		try {
-			System.setProperty(DEFAULT_PROFILES_PROPERTY_NAME, "${spring.profiles.default}");
-			assertThatIllegalArgumentException().isThrownBy(environment::getDefaultProfiles);
+			System.setProperty(DEFAULT_PROFILES_PROPERTY_NAME, "d0");
+			assertThat(environment.getDefaultProfiles()).containsExactly("d0");
+			environment.setDefaultProfiles("d1", "d2");
+			assertThat(environment.getDefaultProfiles()).containsExactly("d1","d2");
 		}
 		finally {
 			System.clearProperty(DEFAULT_PROFILES_PROPERTY_NAME);
@@ -220,40 +207,23 @@ public class StandardEnvironmentTests {
 	}
 
 	@Test
-	void getActiveProfiles_systemPropertiesEmpty() {
-		assertThat(environment.getActiveProfiles().length).isEqualTo(0);
-		System.setProperty(ACTIVE_PROFILES_PROPERTY_NAME, "");
-		assertThat(environment.getActiveProfiles().length).isEqualTo(0);
-		System.clearProperty(ACTIVE_PROFILES_PROPERTY_NAME);
-	}
-
-	@Test
-	void getActiveProfiles_fromSystemProperties() {
-		System.setProperty(ACTIVE_PROFILES_PROPERTY_NAME, "foo");
-		assertThat(Arrays.asList(environment.getActiveProfiles())).contains("foo");
-		System.clearProperty(ACTIVE_PROFILES_PROPERTY_NAME);
-	}
-
-	@Test
-	void getActiveProfiles_fromSystemProperties_withMultipleProfiles() {
-		System.setProperty(ACTIVE_PROFILES_PROPERTY_NAME, "foo,bar");
-		assertThat(environment.getActiveProfiles()).contains("foo", "bar");
-		System.clearProperty(ACTIVE_PROFILES_PROPERTY_NAME);
-	}
-
-	@Test
-	void getActiveProfiles_fromSystemProperties_withMultipleProfiles_withWhitespace() {
-		System.setProperty(ACTIVE_PROFILES_PROPERTY_NAME, " bar , baz "); // notice whitespace
-		assertThat(environment.getActiveProfiles()).contains("bar", "baz");
-		System.clearProperty(ACTIVE_PROFILES_PROPERTY_NAME);
+	void defaultProfileWithCircularPlaceholder() {
+		try {
+			System.setProperty(DEFAULT_PROFILES_PROPERTY_NAME, "${spring.profiles.default}");
+			assertThatIllegalArgumentException()
+				.isThrownBy(environment::getDefaultProfiles)
+				.withMessage("Circular placeholder reference 'spring.profiles.default' in property definitions");
+		}
+		finally {
+			System.clearProperty(DEFAULT_PROFILES_PROPERTY_NAME);
+		}
 	}
 
 	@Test
 	void getDefaultProfiles() {
-		assertThat(environment.getDefaultProfiles()).isEqualTo(new String[] {RESERVED_DEFAULT_PROFILE_NAME});
+		assertThat(environment.getDefaultProfiles()).containsExactly(RESERVED_DEFAULT_PROFILE_NAME);
 		environment.getPropertySources().addFirst(new MockPropertySource().withProperty(DEFAULT_PROFILES_PROPERTY_NAME, "pd1"));
-		assertThat(environment.getDefaultProfiles().length).isEqualTo(1);
-		assertThat(Arrays.asList(environment.getDefaultProfiles())).contains("pd1");
+		assertThat(environment.getDefaultProfiles()).containsExactly("pd1");
 	}
 
 	@Test
@@ -261,82 +231,9 @@ public class StandardEnvironmentTests {
 		environment.setDefaultProfiles();
 		assertThat(environment.getDefaultProfiles().length).isEqualTo(0);
 		environment.setDefaultProfiles("pd1");
-		assertThat(Arrays.asList(environment.getDefaultProfiles())).contains("pd1");
+		assertThat(environment.getDefaultProfiles()).containsExactly("pd1");
 		environment.setDefaultProfiles("pd2", "pd3");
-		assertThat(environment.getDefaultProfiles()).doesNotContain("pd1");
-		assertThat(environment.getDefaultProfiles()).contains("pd2", "pd3");
-	}
-
-	@Test
-	void acceptsProfiles_withEmptyArgumentList() {
-		assertThatIllegalArgumentException().isThrownBy(
-				environment::acceptsProfiles);
-	}
-
-	@Test
-	void acceptsProfiles_withNullArgumentList() {
-		assertThatIllegalArgumentException().isThrownBy(() -> environment.acceptsProfiles((String[]) null));
-	}
-
-	@Test
-	void acceptsProfiles_withNullArgument() {
-		assertThatIllegalArgumentException().isThrownBy(() -> environment.acceptsProfiles((String) null));
-	}
-
-	@Test
-	void acceptsProfiles_withEmptyArgument() {
-		assertThatIllegalArgumentException().isThrownBy(() -> environment.acceptsProfiles(""));
-	}
-
-	@Test
-	void acceptsProfiles_activeProfileSetProgrammatically() {
-		assertThat(environment.acceptsProfiles("p1", "p2")).isFalse();
-		environment.setActiveProfiles("p1");
-		assertThat(environment.acceptsProfiles("p1", "p2")).isTrue();
-		environment.setActiveProfiles("p2");
-		assertThat(environment.acceptsProfiles("p1", "p2")).isTrue();
-		environment.setActiveProfiles("p1", "p2");
-		assertThat(environment.acceptsProfiles("p1", "p2")).isTrue();
-	}
-
-	@Test
-	void acceptsProfiles_activeProfileSetViaProperty() {
-		assertThat(environment.acceptsProfiles("p1")).isFalse();
-		environment.getPropertySources().addFirst(new MockPropertySource().withProperty(ACTIVE_PROFILES_PROPERTY_NAME, "p1"));
-		assertThat(environment.acceptsProfiles("p1")).isTrue();
-	}
-
-	@Test
-	void acceptsProfiles_defaultProfile() {
-		assertThat(environment.acceptsProfiles("pd")).isFalse();
-		environment.setDefaultProfiles("pd");
-		assertThat(environment.acceptsProfiles("pd")).isTrue();
-		environment.setActiveProfiles("p1");
-		assertThat(environment.acceptsProfiles("pd")).isFalse();
-		assertThat(environment.acceptsProfiles("p1")).isTrue();
-	}
-
-	@Test
-	void acceptsProfiles_withNotOperator() {
-		assertThat(environment.acceptsProfiles("p1")).isFalse();
-		assertThat(environment.acceptsProfiles("!p1")).isTrue();
-		environment.addActiveProfile("p1");
-		assertThat(environment.acceptsProfiles("p1")).isTrue();
-		assertThat(environment.acceptsProfiles("!p1")).isFalse();
-	}
-
-	@Test
-	void acceptsProfiles_withInvalidNotOperator() {
-		assertThatIllegalArgumentException().isThrownBy(() -> environment.acceptsProfiles("p1", "!"));
-	}
-
-	@Test
-	void acceptsProfiles_withProfileExpression() {
-		assertThat(environment.acceptsProfiles(Profiles.of("p1 & p2"))).isFalse();
-		environment.addActiveProfile("p1");
-		assertThat(environment.acceptsProfiles(Profiles.of("p1 & p2"))).isFalse();
-		environment.addActiveProfile("p2");
-		assertThat(environment.acceptsProfiles(Profiles.of("p1 & p2"))).isTrue();
+		assertThat(environment.getDefaultProfiles()).containsExactly("pd2", "pd3");
 	}
 
 	@Test
@@ -346,88 +243,99 @@ public class StandardEnvironmentTests {
 			protected void validateProfile(String profile) {
 				super.validateProfile(profile);
 				if (profile.contains("-")) {
-					throw new IllegalArgumentException(
-							"Invalid profile [" + profile + "]: must not contain dash character");
+					throw new IllegalArgumentException("Invalid profile [" + profile + "]: must not contain dash character");
 				}
 			}
 		};
 
 		env.addActiveProfile("validProfile"); // succeeds
 
-		assertThatIllegalArgumentException().isThrownBy(() ->
-				env.addActiveProfile("invalid-profile"))
+		assertThatIllegalArgumentException()
+			.isThrownBy(() -> env.addActiveProfile("invalid-profile"))
 			.withMessage("Invalid profile [invalid-profile]: must not contain dash character");
 	}
 
 	@Test
 	void suppressGetenvAccessThroughSystemProperty() {
-		System.setProperty("spring.getenv.ignore", "true");
-		assertThat(environment.getSystemEnvironment().isEmpty()).isTrue();
-		System.clearProperty("spring.getenv.ignore");
+		try {
+			System.setProperty("spring.getenv.ignore", "true");
+			assertThat(environment.getSystemEnvironment()).isEmpty();
+		}
+		finally {
+			System.clearProperty("spring.getenv.ignore");
+		}
 	}
 
 	@Test
 	void suppressGetenvAccessThroughSpringProperty() {
-		SpringProperties.setProperty("spring.getenv.ignore", "true");
-		assertThat(environment.getSystemEnvironment().isEmpty()).isTrue();
-		SpringProperties.setProperty("spring.getenv.ignore", null);
+		try {
+			SpringProperties.setProperty("spring.getenv.ignore", "true");
+			assertThat(environment.getSystemEnvironment()).isEmpty();
+		}
+		finally {
+			SpringProperties.setProperty("spring.getenv.ignore", null);
+		}
 	}
 
 	@Test
 	void suppressGetenvAccessThroughSpringFlag() {
-		SpringProperties.setFlag("spring.getenv.ignore");
-		assertThat(environment.getSystemEnvironment().isEmpty()).isTrue();
-		SpringProperties.setProperty("spring.getenv.ignore", null);
+		try {
+			SpringProperties.setFlag("spring.getenv.ignore");
+			assertThat(environment.getSystemEnvironment()).isEmpty();
+		}
+		finally {
+			SpringProperties.setProperty("spring.getenv.ignore", null);
+		}
 	}
 
 	@Test
 	void getSystemProperties_withAndWithoutSecurityManager() {
-		System.setProperty(ALLOWED_PROPERTY_NAME, ALLOWED_PROPERTY_VALUE);
-		System.setProperty(DISALLOWED_PROPERTY_NAME, DISALLOWED_PROPERTY_VALUE);
-		System.getProperties().put(STRING_PROPERTY_NAME, NON_STRING_PROPERTY_VALUE);
-		System.getProperties().put(NON_STRING_PROPERTY_NAME, STRING_PROPERTY_VALUE);
-
-		{
-			Map<?, ?> systemProperties = environment.getSystemProperties();
-			assertThat(systemProperties).isNotNull();
-			assertThat(System.getProperties()).isSameAs(systemProperties);
-			assertThat(systemProperties.get(ALLOWED_PROPERTY_NAME)).isEqualTo(ALLOWED_PROPERTY_VALUE);
-			assertThat(systemProperties.get(DISALLOWED_PROPERTY_NAME)).isEqualTo(DISALLOWED_PROPERTY_VALUE);
-
-			// non-string keys and values work fine... until the security manager is introduced below
-			assertThat(systemProperties.get(STRING_PROPERTY_NAME)).isEqualTo(NON_STRING_PROPERTY_VALUE);
-			assertThat(systemProperties.get(NON_STRING_PROPERTY_NAME)).isEqualTo(STRING_PROPERTY_VALUE);
-		}
-
-		SecurityManager oldSecurityManager = System.getSecurityManager();
-		SecurityManager securityManager = new SecurityManager() {
-			@Override
-			public void checkPropertiesAccess() {
-				// see https://download.oracle.com/javase/1.5.0/docs/api/java/lang/System.html#getProperties()
-				throw new AccessControlException("Accessing the system properties is disallowed");
-			}
-			@Override
-			public void checkPropertyAccess(String key) {
-				// see https://download.oracle.com/javase/1.5.0/docs/api/java/lang/System.html#getProperty(java.lang.String)
-				if (DISALLOWED_PROPERTY_NAME.equals(key)) {
-					throw new AccessControlException(
-							String.format("Accessing the system property [%s] is disallowed", DISALLOWED_PROPERTY_NAME));
-				}
-			}
-			@Override
-			public void checkPermission(Permission perm) {
-				// allow everything else
-			}
-		};
-
+		SecurityManager originalSecurityManager = System.getSecurityManager();
 		try {
+			System.setProperty(ALLOWED_PROPERTY_NAME, ALLOWED_PROPERTY_VALUE);
+			System.setProperty(DISALLOWED_PROPERTY_NAME, DISALLOWED_PROPERTY_VALUE);
+			System.getProperties().put(STRING_PROPERTY_NAME, NON_STRING_PROPERTY_VALUE);
+			System.getProperties().put(NON_STRING_PROPERTY_NAME, STRING_PROPERTY_VALUE);
+
+			{
+				Map<?, ?> systemProperties = environment.getSystemProperties();
+				assertThat(systemProperties).isNotNull();
+				assertThat(System.getProperties()).isSameAs(systemProperties);
+				assertThat(systemProperties.get(ALLOWED_PROPERTY_NAME)).isEqualTo(ALLOWED_PROPERTY_VALUE);
+				assertThat(systemProperties.get(DISALLOWED_PROPERTY_NAME)).isEqualTo(DISALLOWED_PROPERTY_VALUE);
+
+				// non-string keys and values work fine... until the security manager is introduced below
+				assertThat(systemProperties.get(STRING_PROPERTY_NAME)).isEqualTo(NON_STRING_PROPERTY_VALUE);
+				assertThat(systemProperties.get(NON_STRING_PROPERTY_NAME)).isEqualTo(STRING_PROPERTY_VALUE);
+			}
+
+			SecurityManager securityManager = new SecurityManager() {
+				@Override
+				public void checkPropertiesAccess() {
+					// see https://download.oracle.com/javase/1.5.0/docs/api/java/lang/System.html#getProperties()
+					throw new AccessControlException("Accessing the system properties is disallowed");
+				}
+				@Override
+				public void checkPropertyAccess(String key) {
+					// see https://download.oracle.com/javase/1.5.0/docs/api/java/lang/System.html#getProperty(java.lang.String)
+					if (DISALLOWED_PROPERTY_NAME.equals(key)) {
+						throw new AccessControlException(
+								String.format("Accessing the system property [%s] is disallowed", DISALLOWED_PROPERTY_NAME));
+					}
+				}
+				@Override
+				public void checkPermission(Permission perm) {
+					// allow everything else
+				}
+			};
+
 			System.setSecurityManager(securityManager);
 
 			{
 				Map<?, ?> systemProperties = environment.getSystemProperties();
 				assertThat(systemProperties).isNotNull();
 				assertThat(systemProperties).isInstanceOf(ReadOnlySystemAttributesMap.class);
-				assertThat((String)systemProperties.get(ALLOWED_PROPERTY_NAME)).isEqualTo(ALLOWED_PROPERTY_VALUE);
+				assertThat(systemProperties.get(ALLOWED_PROPERTY_NAME)).isEqualTo(ALLOWED_PROPERTY_VALUE);
 				assertThat(systemProperties.get(DISALLOWED_PROPERTY_NAME)).isNull();
 
 				// nothing we can do here in terms of warning the user that there was
@@ -441,12 +349,12 @@ public class StandardEnvironmentTests {
 				// the user that under these very special conditions (non-object key +
 				// SecurityManager that disallows access to system properties), they
 				// cannot do what they're attempting.
-				assertThatIllegalArgumentException().as("searching with non-string key against ReadOnlySystemAttributesMap").isThrownBy(() ->
-				systemProperties.get(NON_STRING_PROPERTY_NAME));
+				assertThatIllegalArgumentException().as("searching with non-string key against ReadOnlySystemAttributesMap")
+					.isThrownBy(() -> systemProperties.get(NON_STRING_PROPERTY_NAME));
 			}
 		}
 		finally {
-			System.setSecurityManager(oldSecurityManager);
+			System.setSecurityManager(originalSecurityManager);
 			System.clearProperty(ALLOWED_PROPERTY_NAME);
 			System.clearProperty(DISALLOWED_PROPERTY_NAME);
 			System.getProperties().remove(STRING_PROPERTY_NAME);
@@ -499,4 +407,250 @@ public class StandardEnvironmentTests {
 		EnvironmentTestUtils.getModifiableSystemEnvironment().remove(DISALLOWED_PROPERTY_NAME);
 	}
 
+	@Nested
+	class GetActiveProfiles {
+
+		@Test
+		void systemPropertiesEmpty() {
+			assertThat(environment.getActiveProfiles()).isEmpty();
+			try {
+				System.setProperty(ACTIVE_PROFILES_PROPERTY_NAME, "");
+				assertThat(environment.getActiveProfiles()).isEmpty();
+			}
+			finally {
+				System.clearProperty(ACTIVE_PROFILES_PROPERTY_NAME);
+			}
+		}
+
+		@Test
+		void fromSystemProperties() {
+			try {
+				System.setProperty(ACTIVE_PROFILES_PROPERTY_NAME, "foo");
+				assertThat(environment.getActiveProfiles()).containsExactly("foo");
+			}
+			finally {
+				System.clearProperty(ACTIVE_PROFILES_PROPERTY_NAME);
+			}
+		}
+
+		@Test
+		void fromSystemProperties_withMultipleProfiles() {
+			try {
+				System.setProperty(ACTIVE_PROFILES_PROPERTY_NAME, "foo,bar");
+				assertThat(environment.getActiveProfiles()).containsExactly("foo", "bar");
+			}
+			finally {
+				System.clearProperty(ACTIVE_PROFILES_PROPERTY_NAME);
+			}
+		}
+
+		@Test
+		void fromSystemProperties_withMultipleProfiles_withWhitespace() {
+			try {
+				System.setProperty(ACTIVE_PROFILES_PROPERTY_NAME, " bar , baz "); // notice whitespace
+				assertThat(environment.getActiveProfiles()).containsExactly("bar", "baz");
+			}
+			finally {
+				System.clearProperty(ACTIVE_PROFILES_PROPERTY_NAME);
+			}
+		}
+	}
+
+	@Nested
+	class AcceptsProfilesTests {
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void withEmptyArgumentList() {
+			assertThatIllegalArgumentException().isThrownBy(environment::acceptsProfiles);
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void withNullArgumentList() {
+			assertThatIllegalArgumentException().isThrownBy(() -> environment.acceptsProfiles((String[]) null));
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void withNullArgument() {
+			assertThatIllegalArgumentException().isThrownBy(() -> environment.acceptsProfiles((String) null));
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void withEmptyArgument() {
+			assertThatIllegalArgumentException().isThrownBy(() -> environment.acceptsProfiles(""));
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void activeProfileSetProgrammatically() {
+			assertThat(environment.acceptsProfiles("p1", "p2")).isFalse();
+			environment.setActiveProfiles("p1");
+			assertThat(environment.acceptsProfiles("p1", "p2")).isTrue();
+			environment.setActiveProfiles("p2");
+			assertThat(environment.acceptsProfiles("p1", "p2")).isTrue();
+			environment.setActiveProfiles("p1", "p2");
+			assertThat(environment.acceptsProfiles("p1", "p2")).isTrue();
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void activeProfileSetViaProperty() {
+			assertThat(environment.acceptsProfiles("p1")).isFalse();
+			environment.getPropertySources().addFirst(new MockPropertySource().withProperty(ACTIVE_PROFILES_PROPERTY_NAME, "p1"));
+			assertThat(environment.acceptsProfiles("p1")).isTrue();
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void defaultProfile() {
+			assertThat(environment.acceptsProfiles("pd")).isFalse();
+			environment.setDefaultProfiles("pd");
+			assertThat(environment.acceptsProfiles("pd")).isTrue();
+			environment.setActiveProfiles("p1");
+			assertThat(environment.acceptsProfiles("pd")).isFalse();
+			assertThat(environment.acceptsProfiles("p1")).isTrue();
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void withNotOperator() {
+			assertThat(environment.acceptsProfiles("p1")).isFalse();
+			assertThat(environment.acceptsProfiles("!p1")).isTrue();
+			environment.addActiveProfile("p1");
+			assertThat(environment.acceptsProfiles("p1")).isTrue();
+			assertThat(environment.acceptsProfiles("!p1")).isFalse();
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void withInvalidNotOperator() {
+			assertThatIllegalArgumentException().isThrownBy(() -> environment.acceptsProfiles("p1", "!"));
+		}
+
+		@Test
+		void withProfileExpression() {
+			assertThat(environment.acceptsProfiles(Profiles.of("p1 & p2"))).isFalse();
+			environment.addActiveProfile("p1");
+			assertThat(environment.acceptsProfiles(Profiles.of("p1 & p2"))).isFalse();
+			environment.addActiveProfile("p2");
+			assertThat(environment.acceptsProfiles(Profiles.of("p1 & p2"))).isTrue();
+		}
+
+	}
+
+	@Nested
+	class MatchesProfilesTests {
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void withEmptyArgumentList() {
+			assertThatIllegalArgumentException().isThrownBy(environment::matchesProfiles);
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void withNullArgumentList() {
+			assertThatIllegalArgumentException().isThrownBy(() -> environment.matchesProfiles((String[]) null));
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void withNullArgument() {
+			assertThatIllegalArgumentException().isThrownBy(() -> environment.matchesProfiles((String) null));
+			assertThatIllegalArgumentException().isThrownBy(() -> environment.matchesProfiles("p1", null));
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void withEmptyArgument() {
+			assertThatIllegalArgumentException().isThrownBy(() -> environment.matchesProfiles(""));
+			assertThatIllegalArgumentException().isThrownBy(() -> environment.matchesProfiles("p1", ""));
+			assertThatIllegalArgumentException().isThrownBy(() -> environment.matchesProfiles("p1", "      "));
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void withInvalidNotOperator() {
+			assertThatIllegalArgumentException().isThrownBy(() -> environment.matchesProfiles("p1", "!"));
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void withInvalidCompoundExpressionGrouping() {
+			assertThatIllegalArgumentException().isThrownBy(() -> environment.matchesProfiles("p1 | p2 & p3"));
+			assertThatIllegalArgumentException().isThrownBy(() -> environment.matchesProfiles("p1 & p2 | p3"));
+			assertThatIllegalArgumentException().isThrownBy(() -> environment.matchesProfiles("p1 & (p2 | p3) | p4"));
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void activeProfileSetProgrammatically() {
+			assertThat(environment.matchesProfiles("p1", "p2")).isFalse();
+
+			environment.setActiveProfiles("p1");
+			assertThat(environment.matchesProfiles("p1", "p2")).isTrue();
+
+			environment.setActiveProfiles("p2");
+			assertThat(environment.matchesProfiles("p1", "p2")).isTrue();
+
+			environment.setActiveProfiles("p1", "p2");
+			assertThat(environment.matchesProfiles("p1", "p2")).isTrue();
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void activeProfileSetViaProperty() {
+			assertThat(environment.matchesProfiles("p1")).isFalse();
+
+			environment.getPropertySources().addFirst(new MockPropertySource().withProperty(ACTIVE_PROFILES_PROPERTY_NAME, "p1"));
+			assertThat(environment.matchesProfiles("p1")).isTrue();
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void defaultProfile() {
+			assertThat(environment.matchesProfiles("pd")).isFalse();
+
+			environment.setDefaultProfiles("pd");
+			assertThat(environment.matchesProfiles("pd")).isTrue();
+
+			environment.setActiveProfiles("p1");
+			assertThat(environment.matchesProfiles("pd")).isFalse();
+			assertThat(environment.matchesProfiles("p1")).isTrue();
+		}
+
+		@Test
+		@SuppressWarnings("deprecation")
+		void withNotOperator() {
+			assertThat(environment.matchesProfiles("p1")).isFalse();
+			assertThat(environment.matchesProfiles("!p1")).isTrue();
+
+			environment.addActiveProfile("p1");
+			assertThat(environment.matchesProfiles("p1")).isTrue();
+			assertThat(environment.matchesProfiles("!p1")).isFalse();
+		}
+
+		@Test
+		void withProfileExpressions() {
+			assertThat(environment.matchesProfiles("p1 & p2")).isFalse();
+
+			environment.addActiveProfile("p1");
+			assertThat(environment.matchesProfiles("p1 | p2")).isTrue();
+			assertThat(environment.matchesProfiles("p1 & p2")).isFalse();
+
+			environment.addActiveProfile("p2");
+			assertThat(environment.matchesProfiles("p1 & p2")).isTrue();
+			assertThat(environment.matchesProfiles("p1 | p2")).isTrue();
+			assertThat(environment.matchesProfiles("foo | p1", "p2")).isTrue();
+			assertThat(environment.matchesProfiles("foo | p2", "p1")).isTrue();
+			assertThat(environment.matchesProfiles("foo | (p2 & p1)")).isTrue();
+			assertThat(environment.matchesProfiles("p2 & (foo | p1)")).isTrue();
+			assertThat(environment.matchesProfiles("foo", "(p2 & p1)")).isTrue();
+		}
+
+	}
+
 }

spring-core/src/test/java/org/springframework/util/ObjectUtilsTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,15 +17,26 @@
 package org.springframework.util;
 
 import java.io.IOException;
+import java.net.URI;
+import java.net.URL;
 import java.sql.SQLException;
+import java.time.LocalDate;
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
+import java.util.Date;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.List;
+import java.util.Locale;
 import java.util.Set;
+import java.util.UUID;
 
+import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.springframework.util.ObjectUtils.isEmpty;
 
@@ -816,13 +827,156 @@ class ObjectUtilsTests {
 			.withMessage("Constant [bogus] does not exist in enum type org.springframework.util.ObjectUtilsTests$Tropes");
 	}
 
-	private void assertEqualHashCodes(int expected, Object array) {
+
+	private static void assertEqualHashCodes(int expected, Object array) {
 		int actual = ObjectUtils.nullSafeHashCode(array);
 		assertThat(actual).isEqualTo(expected);
-		assertThat(array.hashCode() != actual).isTrue();
+		assertThat(array.hashCode()).isNotEqualTo(actual);
 	}
 
 
 	enum Tropes {FOO, BAR, baz}
 
+
+	@Nested
+	class NullSafeConciseToStringTests {
+
+		private final String truncated = " (truncated)...";
+		private final int truncatedLength = 100 + truncated.length();
+
+		@Test
+		void nullSafeConciseToStringForNull() {
+			assertThat(ObjectUtils.nullSafeConciseToString(null)).isEqualTo("null");
+		}
+
+		@Test
+		void nullSafeConciseToStringForClass() {
+			assertThat(ObjectUtils.nullSafeConciseToString(String.class)).isEqualTo("java.lang.String");
+		}
+
+		@Test
+		void nullSafeConciseToStringForStrings() {
+			String repeat100 = repeat("X", 100);
+			String repeat101 = repeat("X", 101);
+
+			assertThat(ObjectUtils.nullSafeConciseToString("")).isEqualTo("");
+			assertThat(ObjectUtils.nullSafeConciseToString("foo")).isEqualTo("foo");
+			assertThat(ObjectUtils.nullSafeConciseToString(repeat100)).isEqualTo(repeat100);
+			assertThat(ObjectUtils.nullSafeConciseToString(repeat101)).hasSize(truncatedLength).endsWith(truncated);
+		}
+
+		@Test
+		void nullSafeConciseToStringForStringBuilders() {
+			String repeat100 = repeat("X", 100);
+			String repeat101 = repeat("X", 101);
+
+			assertThat(ObjectUtils.nullSafeConciseToString(new StringBuilder("foo"))).isEqualTo("foo");
+			assertThat(ObjectUtils.nullSafeConciseToString(new StringBuilder(repeat100))).isEqualTo(repeat100);
+			assertThat(ObjectUtils.nullSafeConciseToString(new StringBuilder(repeat101))).hasSize(truncatedLength).endsWith(truncated);
+		}
+
+		@Test
+		void nullSafeConciseToStringForEnum() {
+			assertThat(ObjectUtils.nullSafeConciseToString(Tropes.FOO)).isEqualTo("FOO");
+		}
+
+		@Test
+		void nullSafeConciseToStringForNumber() {
+			assertThat(ObjectUtils.nullSafeConciseToString(42L)).isEqualTo("42");
+			assertThat(ObjectUtils.nullSafeConciseToString(99.1234D)).isEqualTo("99.1234");
+		}
+
+		@Test
+		void nullSafeConciseToStringForDate() {
+			Date date = new Date();
+			assertThat(ObjectUtils.nullSafeConciseToString(date)).isEqualTo(date.toString());
+		}
+
+		@Test
+		void nullSafeConciseToStringForTemporal() {
+			LocalDate localDate = LocalDate.now();
+			assertThat(ObjectUtils.nullSafeConciseToString(localDate)).isEqualTo(localDate.toString());
+		}
+
+		@Test
+		void nullSafeConciseToStringForUUID() {
+			UUID id = UUID.randomUUID();
+			assertThat(ObjectUtils.nullSafeConciseToString(id)).isEqualTo(id.toString());
+		}
+
+		@Test
+		void nullSafeConciseToStringForURI() {
+			String uri = "https://www.example.com/?foo=1&bar=2&baz=3";
+			assertThat(ObjectUtils.nullSafeConciseToString(URI.create(uri))).isEqualTo(uri);
+
+			uri += "&qux=" + repeat("4", 60);
+			assertThat(ObjectUtils.nullSafeConciseToString(URI.create(uri)))
+					.hasSize(truncatedLength)
+					.startsWith(uri.subSequence(0, 100))
+					.endsWith(truncated);
+		}
+
+		@Test
+		void nullSafeConciseToStringForURL() throws Exception {
+			String url = "https://www.example.com/?foo=1&bar=2&baz=3";
+			assertThat(ObjectUtils.nullSafeConciseToString(new URL(url))).isEqualTo(url);
+
+			url += "&qux=" + repeat("4", 60);
+			assertThat(ObjectUtils.nullSafeConciseToString(new URL(url)))
+					.hasSize(truncatedLength)
+					.startsWith(url.subSequence(0, 100))
+					.endsWith(truncated);
+		}
+
+		@Test
+		void nullSafeConciseToStringForLocale() {
+			assertThat(ObjectUtils.nullSafeConciseToString(Locale.GERMANY)).isEqualTo("de_DE");
+		}
+
+		@Test
+		void nullSafeConciseToStringForArraysAndCollections() {
+			List<String> list = Arrays.asList("a", "b", "c");
+			assertThat(ObjectUtils.nullSafeConciseToString(new int[][] {{1, 2}, {3, 4}})).startsWith(prefix(int[][].class));
+			assertThat(ObjectUtils.nullSafeConciseToString(list.toArray(new Object[0]))).startsWith(prefix(Object[].class));
+			assertThat(ObjectUtils.nullSafeConciseToString(list.toArray(new String[0]))).startsWith(prefix(String[].class));
+			assertThat(ObjectUtils.nullSafeConciseToString(new ArrayList<>(list))).startsWith(prefix(ArrayList.class));
+			assertThat(ObjectUtils.nullSafeConciseToString(new HashSet<>(list))).startsWith(prefix(HashSet.class));
+		}
+
+		@Test
+		void nullSafeConciseToStringForCustomTypes() {
+			class ExplosiveType {
+				@Override
+				public String toString() {
+					throw new UnsupportedOperationException("no-go");
+				}
+			}
+			ExplosiveType explosiveType = new ExplosiveType();
+			assertThatExceptionOfType(UnsupportedOperationException.class).isThrownBy(explosiveType::toString);
+			assertThat(ObjectUtils.nullSafeConciseToString(explosiveType)).startsWith(prefix(ExplosiveType.class));
+
+			class WordyType {
+				@Override
+				public String toString() {
+					return repeat("blah blah", 20);
+				}
+			}
+			WordyType wordyType = new WordyType();
+			assertThat(wordyType).asString().hasSizeGreaterThanOrEqualTo(180 /* 9x20 */);
+			assertThat(ObjectUtils.nullSafeConciseToString(wordyType)).startsWith(prefix(WordyType.class));
+		}
+
+		private String repeat(String str, int count) {
+			String result = "";
+			for (int i = 0; i < count; i++) {
+				result += str;
+			}
+			return result;
+		}
+
+		private String prefix(Class<?> clazz) {
+			return clazz.getTypeName() + "@";
+		}
+	}
+
 }

spring-core/src/test/java/org/springframework/util/StringUtilsTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,6 +22,8 @@ import java.util.Locale;
 import java.util.Properties;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
@@ -785,4 +787,26 @@ class StringUtilsTests {
 		assertThat(StringUtils.collectionToCommaDelimitedString(Collections.singletonList(null))).isEqualTo("null");
 	}
 
+	@Test
+	void truncatePreconditions() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> StringUtils.truncate("foo", 0))
+				.withMessage("Truncation threshold must be a positive number: 0");
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> StringUtils.truncate("foo", -99))
+				.withMessage("Truncation threshold must be a positive number: -99");
+	}
+
+	@ParameterizedTest
+	@CsvSource(delimiterString = "-->", value = {
+		"''                  --> ''",
+		"aardvark            --> aardvark",
+		"aardvark12          --> aardvark12",
+		"aardvark123         --> aardvark12 (truncated)...",
+		"aardvark, bird, cat --> aardvark,  (truncated)..."
+	})
+	void truncate(String text, String truncated) {
+		assertThat(StringUtils.truncate(text, 10)).isEqualTo(truncated);
+	}
+
 }

spring-expression/src/main/java/org/springframework/expression/EvaluationContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package org.springframework.expression;
 
 import java.util.List;
+import java.util.function.Supplier;
 
 import org.springframework.lang.Nullable;
 
@@ -24,12 +25,21 @@ import org.springframework.lang.Nullable;
  * Expressions are executed in an evaluation context. It is in this context that
  * references are resolved when encountered during expression evaluation.
  *
- * <p>There is a default implementation of this EvaluationContext interface:
- * {@link org.springframework.expression.spel.support.StandardEvaluationContext}
- * which can be extended, rather than having to implement everything manually.
+ * <p>There are two default implementations of this interface.
+ * <ul>
+ * <li>{@link org.springframework.expression.spel.support.SimpleEvaluationContext
+ * SimpleEvaluationContext}: a simpler builder-style {@code EvaluationContext}
+ * variant for data-binding purposes, which allows for opting into several SpEL
+ * features as needed.</li>
+ * <li>{@link org.springframework.expression.spel.support.StandardEvaluationContext
+ * StandardEvaluationContext}: a powerful and highly configurable {@code EvaluationContext}
+ * implementation, which can be extended, rather than having to implement everything
+ * manually.</li>
+ * </ul>
  *
  * @author Andy Clement
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @since 3.0
  */
 public interface EvaluationContext {
@@ -85,7 +95,30 @@ public interface EvaluationContext {
 	OperatorOverloader getOperatorOverloader();
 
 	/**
-	 * Set a named variable within this evaluation context to a specified value.
+	 * Assign the value created by the specified {@link Supplier} to a named variable
+	 * within this evaluation context.
+	 * <p>In contrast to {@link #setVariable(String, Object)}, this method should only
+	 * be invoked to support the assignment operator ({@code =}) within an expression.
+	 * <p>By default, this method delegates to {@code setVariable(String, Object)},
+	 * providing the value created by the {@code valueSupplier}. Concrete implementations
+	 * may override this <em>default</em> method to provide different semantics.
+	 * @param name the name of the variable to assign
+	 * @param valueSupplier the supplier of the value to be assigned to the variable
+	 * @return a {@link TypedValue} wrapping the assigned value
+	 * @since 5.2.24
+	 */
+	default TypedValue assignVariable(String name, Supplier<TypedValue> valueSupplier) {
+		TypedValue typedValue = valueSupplier.get();
+		setVariable(name, typedValue.getValue());
+		return typedValue;
+	}
+
+	/**
+	 * Set a named variable in this evaluation context to a specified value.
+	 * <p>In contrast to {@link #assignVariable(String, Supplier)}, this method
+	 * should only be invoked programmatically when interacting directly with the
+	 * {@code EvaluationContext} &mdash; for example, to provide initial
+	 * configuration for the context.
 	 * @param name the name of the variable to set
 	 * @param value the value to be placed in the variable
 	 */
@@ -93,7 +126,7 @@ public interface EvaluationContext {
 
 	/**
 	 * Look up a named variable within this evaluation context.
-	 * @param name variable to lookup
+	 * @param name the name of the variable to look up
 	 * @return the value of the variable, or {@code null} if not found
 	 */
 	@Nullable

spring-expression/src/main/java/org/springframework/expression/common/TemplateAwareExpressionParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,6 +26,7 @@ import org.springframework.expression.ExpressionParser;
 import org.springframework.expression.ParseException;
 import org.springframework.expression.ParserContext;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * An expression parser that understands templates. It can be subclassed by expression
@@ -34,6 +35,7 @@ import org.springframework.lang.Nullable;
  * @author Keith Donald
  * @author Juergen Hoeller
  * @author Andy Clement
+ * @author Sam Brannen
  * @since 3.0
  */
 public abstract class TemplateAwareExpressionParser implements ExpressionParser {
@@ -46,9 +48,11 @@ public abstract class TemplateAwareExpressionParser implements ExpressionParser
 	@Override
 	public Expression parseExpression(String expressionString, @Nullable ParserContext context) throws ParseException {
 		if (context != null && context.isTemplate()) {
+			Assert.notNull(expressionString, "'expressionString' must not be null");
 			return parseTemplate(expressionString, context);
 		}
 		else {
+			Assert.hasText(expressionString, "'expressionString' must not be null or blank");
 			return doParseExpression(expressionString, context);
 		}
 	}

spring-expression/src/main/java/org/springframework/expression/spel/ExpressionState.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,6 +23,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
+import java.util.function.Supplier;
 
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.expression.EvaluationContext;
@@ -38,18 +39,19 @@ import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 
 /**
- * An ExpressionState is for maintaining per-expression-evaluation state, any changes to
- * it are not seen by other expressions but it gives a place to hold local variables and
+ * ExpressionState is for maintaining per-expression-evaluation state: any changes to
+ * it are not seen by other expressions, but it gives a place to hold local variables and
  * for component expressions in a compound expression to communicate state. This is in
  * contrast to the EvaluationContext, which is shared amongst expression evaluations, and
  * any changes to it will be seen by other expressions or any code that chooses to ask
  * questions of the context.
  *
- * <p>It also acts as a place for to define common utility routines that the various AST
+ * <p>It also acts as a place to define common utility routines that the various AST
  * nodes might need.
  *
  * @author Andy Clement
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @since 3.0
  */
 public class ExpressionState {
@@ -138,6 +140,29 @@ public class ExpressionState {
 		return this.scopeRootObjects.element();
 	}
 
+	/**
+	 * Assign the value created by the specified {@link Supplier} to a named variable
+	 * within the evaluation context.
+	 * <p>In contrast to {@link #setVariable(String, Object)}, this method should
+	 * only be invoked to support assignment within an expression.
+	 * @param name the name of the variable to assign
+	 * @param valueSupplier the supplier of the value to be assigned to the variable
+	 * @return a {@link TypedValue} wrapping the assigned value
+	 * @since 5.2.24
+	 * @see EvaluationContext#assignVariable(String, Supplier)
+	 */
+	public TypedValue assignVariable(String name, Supplier<TypedValue> valueSupplier) {
+		return this.relatedContext.assignVariable(name, valueSupplier);
+	}
+
+	/**
+	 * Set a named variable in the evaluation context to a specified value.
+	 * <p>In contrast to {@link #assignVariable(String, Supplier)}, this method
+	 * should only be invoked programmatically.
+	 * @param name the name of the variable to set
+	 * @param value the value to be placed in the variable
+	 * @see EvaluationContext#setVariable(String, Object)
+	 */
 	public void setVariable(String name, @Nullable Object value) {
 		this.relatedContext.setVariable(name, value);
 	}

spring-expression/src/main/java/org/springframework/expression/spel/SpelMessage.java

@@ -266,13 +266,25 @@ public enum SpelMessage {
 	MAX_ARRAY_ELEMENTS_THRESHOLD_EXCEEDED(Kind.ERROR, 1075,
 			"Array declares too many elements, exceeding the threshold of ''{0}''"),
 
-	/** @since 5.3.26 */
+	/** @since 5.2.23 */
 	MAX_REPEATED_TEXT_SIZE_EXCEEDED(Kind.ERROR, 1076,
-			"Repeated text results in too many characters, exceeding the threshold of ''{0}''"),
+			"Repeated text is too long, exceeding the threshold of ''{0}'' characters"),
 
-	/** @since 5.3.26 */
+	/** @since 5.2.23 */
 	MAX_REGEX_LENGTH_EXCEEDED(Kind.ERROR, 1077,
-			"Regular expression contains too many characters, exceeding the threshold of ''{0}''");
+			"Regular expression is too long, exceeding the threshold of ''{0}'' characters"),
+
+	/** @since 5.2.24 */
+	MAX_CONCATENATED_STRING_LENGTH_EXCEEDED(Kind.ERROR, 1078,
+			"Concatenated string is too long, exceeding the threshold of ''{0}'' characters"),
+
+	/** @since 5.2.24 */
+	MAX_EXPRESSION_LENGTH_EXCEEDED(Kind.ERROR, 1079,
+			"SpEL expression is too long, exceeding the threshold of ''{0}'' characters"),
+
+	/** @since 5.2.24 */
+	VARIABLE_ASSIGNMENT_NOT_SUPPORTED(Kind.ERROR, 1080,
+			"Assignment to variable ''{0}'' is not supported");
 
 
 	private final Kind kind;

spring-expression/src/main/java/org/springframework/expression/spel/SpelParserConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,6 +30,12 @@ import org.springframework.lang.Nullable;
  */
 public class SpelParserConfiguration {
 
+	/**
+	 * Default maximum length permitted for a SpEL expression.
+	 * @since 5.2.24
+	 */
+	private static final int DEFAULT_MAX_EXPRESSION_LENGTH = 10_000;
+
 	/** System property to configure the default compiler mode for SpEL expression parsers: {@value}. */
 	public static final String SPRING_EXPRESSION_COMPILER_MODE_PROPERTY_NAME = "spring.expression.compiler.mode";
 
@@ -54,6 +60,8 @@ public class SpelParserConfiguration {
 
 	private final int maximumAutoGrowSize;
 
+	private final int maximumExpressionLength;
+
 
 	/**
 	 * Create a new {@code SpelParserConfiguration} instance with default settings.
@@ -102,11 +110,30 @@ public class SpelParserConfiguration {
 	public SpelParserConfiguration(@Nullable SpelCompilerMode compilerMode, @Nullable ClassLoader compilerClassLoader,
 			boolean autoGrowNullReferences, boolean autoGrowCollections, int maximumAutoGrowSize) {
 
+		this(compilerMode, compilerClassLoader, autoGrowNullReferences, autoGrowCollections,
+				maximumAutoGrowSize, DEFAULT_MAX_EXPRESSION_LENGTH);
+	}
+
+	/**
+	 * Create a new {@code SpelParserConfiguration} instance.
+	 * @param compilerMode the compiler mode that parsers using this configuration object should use
+	 * @param compilerClassLoader the ClassLoader to use as the basis for expression compilation
+	 * @param autoGrowNullReferences if null references should automatically grow
+	 * @param autoGrowCollections if collections should automatically grow
+	 * @param maximumAutoGrowSize the maximum size that a collection can auto grow
+	 * @param maximumExpressionLength the maximum length of a SpEL expression;
+	 * must be a positive number
+	 * @since 5.2.25
+	 */
+	public SpelParserConfiguration(@Nullable SpelCompilerMode compilerMode, @Nullable ClassLoader compilerClassLoader,
+			boolean autoGrowNullReferences, boolean autoGrowCollections, int maximumAutoGrowSize, int maximumExpressionLength) {
+
 		this.compilerMode = (compilerMode != null ? compilerMode : defaultCompilerMode);
 		this.compilerClassLoader = compilerClassLoader;
 		this.autoGrowNullReferences = autoGrowNullReferences;
 		this.autoGrowCollections = autoGrowCollections;
 		this.maximumAutoGrowSize = maximumAutoGrowSize;
+		this.maximumExpressionLength = maximumExpressionLength;
 	}
 
 
@@ -146,4 +173,12 @@ public class SpelParserConfiguration {
 		return this.maximumAutoGrowSize;
 	}
 
+	/**
+	 * Return the maximum number of characters that a SpEL expression can contain.
+	 * @since 5.2.25
+	 */
+	public int getMaximumExpressionLength() {
+		return this.maximumExpressionLength;
+	}
+
 }

spring-expression/src/main/java/org/springframework/expression/spel/ast/Assign.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,6 +27,7 @@ import org.springframework.expression.spel.ExpressionState;
  * <p>Example: 'someNumberProperty=42'
  *
  * @author Andy Clement
+ * @author Sam Brannen
  * @since 3.0
  */
 public class Assign extends SpelNodeImpl {
@@ -38,9 +39,7 @@ public class Assign extends SpelNodeImpl {
 
 	@Override
 	public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
-		TypedValue newValue = this.children[1].getValueInternal(state);
-		getChild(0).setValue(state, newValue.getValue());
-		return newValue;
+		return this.children[0].setValueInternal(state, () -> this.children[1].getValueInternal(state));
 	}
 
 	@Override

spring-expression/src/main/java/org/springframework/expression/spel/ast/CompoundExpression.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package org.springframework.expression.spel.ast;
 
 import java.util.StringJoiner;
+import java.util.function.Supplier;
 
 import org.springframework.asm.MethodVisitor;
 import org.springframework.expression.EvaluationException;
@@ -24,13 +25,13 @@ import org.springframework.expression.TypedValue;
 import org.springframework.expression.spel.CodeFlow;
 import org.springframework.expression.spel.ExpressionState;
 import org.springframework.expression.spel.SpelEvaluationException;
-import org.springframework.lang.Nullable;
 
 /**
  * Represents a DOT separated expression sequence, such as
  * {@code 'property1.property2.methodOne()'}.
  *
  * @author Andy Clement
+ * @author Sam Brannen
  * @since 3.0
  */
 public class CompoundExpression extends SpelNodeImpl {
@@ -95,8 +96,12 @@ public class CompoundExpression extends SpelNodeImpl {
 	}
 
 	@Override
-	public void setValue(ExpressionState state, @Nullable Object value) throws EvaluationException {
-		getValueRef(state).setValue(value);
+	public TypedValue setValueInternal(ExpressionState state, Supplier<TypedValue> valueSupplier)
+			throws EvaluationException {
+
+		TypedValue typedValue = valueSupplier.get();
+		getValueRef(state).setValue(typedValue.getValue());
+		return typedValue;
 	}
 
 	@Override

spring-expression/src/main/java/org/springframework/expression/spel/ast/Indexer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,6 +25,7 @@ import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.StringJoiner;
+import java.util.function.Supplier;
 
 import org.springframework.asm.MethodVisitor;
 import org.springframework.core.convert.TypeDescriptor;
@@ -45,11 +46,12 @@ import org.springframework.util.ReflectionUtils;
 
 /**
  * An Indexer can index into some proceeding structure to access a particular piece of it.
- * Supported structures are: strings / collections (lists/sets) / arrays.
+ * <p>Supported structures are: strings / collections (lists/sets) / arrays.
  *
  * @author Andy Clement
  * @author Phillip Webb
  * @author Stephane Nicoll
+ * @author Sam Brannen
  * @since 3.0
  */
 // TODO support multidimensional arrays
@@ -102,8 +104,12 @@ public class Indexer extends SpelNodeImpl {
 	}
 
 	@Override
-	public void setValue(ExpressionState state, @Nullable Object newValue) throws EvaluationException {
-		getValueRef(state).setValue(newValue);
+	public TypedValue setValueInternal(ExpressionState state, Supplier<TypedValue> valueSupplier)
+			throws EvaluationException {
+
+		TypedValue typedValue = valueSupplier.get();
+		getValueRef(state).setValue(typedValue.getValue());
+		return typedValue;
 	}
 
 	@Override

spring-expression/src/main/java/org/springframework/expression/spel/ast/OpMultiply.java

@@ -56,7 +56,7 @@ public class OpMultiply extends Operator {
 
 	/**
 	 * Maximum number of characters permitted in repeated text.
-	 * @since 5.3.26
+	 * @since 5.2.23
 	 */
 	private static final int MAX_REPEATED_TEXT_SIZE = 256;
 

spring-expression/src/main/java/org/springframework/expression/spel/ast/OpPlus.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,6 +27,8 @@ import org.springframework.expression.TypeConverter;
 import org.springframework.expression.TypedValue;
 import org.springframework.expression.spel.CodeFlow;
 import org.springframework.expression.spel.ExpressionState;
+import org.springframework.expression.spel.SpelEvaluationException;
+import org.springframework.expression.spel.SpelMessage;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.NumberUtils;
@@ -46,10 +48,18 @@ import org.springframework.util.NumberUtils;
  * @author Juergen Hoeller
  * @author Ivo Smid
  * @author Giovanni Dall'Oglio Risso
+ * @author Sam Brannen
  * @since 3.0
  */
 public class OpPlus extends Operator {
 
+	/**
+	 * Maximum number of characters permitted in a concatenated string.
+	 * @since 5.2.24
+	 */
+	private static final int MAX_CONCATENATED_STRING_LENGTH = 100_000;
+
+
 	public OpPlus(int startPos, int endPos, SpelNodeImpl... operands) {
 		super("+", startPos, endPos, operands);
 		Assert.notEmpty(operands, "Operands must not be empty");
@@ -123,22 +133,45 @@ public class OpPlus extends Operator {
 
 		if (leftOperand instanceof String && rightOperand instanceof String) {
 			this.exitTypeDescriptor = "Ljava/lang/String";
-			return new TypedValue((String) leftOperand + rightOperand);
+			String leftString = (String) leftOperand;
+			String rightString = (String) rightOperand;
+			checkStringLength(leftString);
+			checkStringLength(rightString);
+			return concatenate(leftString, rightString);
 		}
 
 		if (leftOperand instanceof String) {
-			return new TypedValue(
-					leftOperand + (rightOperand == null ? "null" : convertTypedValueToString(operandTwoValue, state)));
+			String leftString = (String) leftOperand;
+			checkStringLength(leftString);
+			String rightString = (rightOperand == null ? "null" : convertTypedValueToString(operandTwoValue, state));
+			checkStringLength(rightString);
+			return concatenate(leftString, rightString);
 		}
 
 		if (rightOperand instanceof String) {
-			return new TypedValue(
-					(leftOperand == null ? "null" : convertTypedValueToString(operandOneValue, state)) + rightOperand);
+			String rightString = (String) rightOperand;
+			checkStringLength(rightString);
+			String leftString = (leftOperand == null ? "null" : convertTypedValueToString(operandOneValue, state));
+			checkStringLength(leftString);
+			return concatenate(leftString, rightString);
 		}
 
 		return state.operate(Operation.ADD, leftOperand, rightOperand);
 	}
 
+	private void checkStringLength(String string) {
+		if (string.length() > MAX_CONCATENATED_STRING_LENGTH) {
+			throw new SpelEvaluationException(getStartPosition(),
+					SpelMessage.MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, MAX_CONCATENATED_STRING_LENGTH);
+		}
+	}
+
+	private TypedValue concatenate(String leftString, String rightString) {
+		String result = leftString + rightString;
+		checkStringLength(result);
+		return new TypedValue(result);
+	}
+
 	@Override
 	public String toStringAST() {
 		if (this.children.length < 2) {  // unary plus

spring-expression/src/main/java/org/springframework/expression/spel/ast/OperatorMatches.java

@@ -45,16 +45,16 @@ public class OperatorMatches extends Operator {
 
 	/**
 	 * Maximum number of characters permitted in a regular expression.
-	 * @since 5.3.26
+	 * @since 5.2.23
 	 */
-	private static final int MAX_REGEX_LENGTH = 256;
+	private static final int MAX_REGEX_LENGTH = 1000;
 
 	private final ConcurrentMap<String, Pattern> patternCache;
 
 
 	/**
 	 * Create a new {@link OperatorMatches} instance.
-	 * @deprecated as of Spring Framework 5.3.26 in favor of invoking
+	 * @deprecated as of Spring Framework 5.2.23 in favor of invoking
 	 * {@link #OperatorMatches(ConcurrentMap, int, int, SpelNodeImpl...)}
 	 * with a shared pattern cache instead
 	 */
@@ -65,7 +65,7 @@ public class OperatorMatches extends Operator {
 
 	/**
 	 * Create a new {@link OperatorMatches} instance with a shared pattern cache.
-	 * @since 5.3.26
+	 * @since 5.2.23
 	 */
 	public OperatorMatches(ConcurrentMap<String, Pattern> patternCache, int startPos, int endPos, SpelNodeImpl... operands) {
 		super("matches", startPos, endPos, operands);

spring-expression/src/main/java/org/springframework/expression/spel/ast/PropertyOrFieldReference.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@ import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.function.Supplier;
 
 import org.springframework.asm.Label;
 import org.springframework.asm.MethodVisitor;
@@ -46,6 +47,7 @@ import org.springframework.util.ReflectionUtils;
  * @author Andy Clement
  * @author Juergen Hoeller
  * @author Clark Duplichien
+ * @author Sam Brannen
  * @since 3.0
  */
 public class PropertyOrFieldReference extends SpelNodeImpl {
@@ -147,8 +149,12 @@ public class PropertyOrFieldReference extends SpelNodeImpl {
 	}
 
 	@Override
-	public void setValue(ExpressionState state, @Nullable Object newValue) throws EvaluationException {
-		writeProperty(state.getActiveContextObject(), state.getEvaluationContext(), this.name, newValue);
+	public TypedValue setValueInternal(ExpressionState state, Supplier<TypedValue> valueSupplier)
+			throws EvaluationException {
+
+		TypedValue typedValue = valueSupplier.get();
+		writeProperty(state.getActiveContextObject(), state.getEvaluationContext(), this.name, typedValue.getValue());
+		return typedValue;
 	}
 
 	@Override

spring-expression/src/main/java/org/springframework/expression/spel/ast/SpelNodeImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,7 @@ package org.springframework.expression.spel.ast;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Member;
 import java.lang.reflect.Method;
+import java.util.function.Supplier;
 
 import org.springframework.asm.MethodVisitor;
 import org.springframework.asm.Opcodes;
@@ -40,6 +41,7 @@ import org.springframework.util.ObjectUtils;
  *
  * @author Andy Clement
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @since 3.0
  */
 public abstract class SpelNodeImpl implements SpelNode, Opcodes {
@@ -64,7 +66,7 @@ public abstract class SpelNodeImpl implements SpelNode, Opcodes {
 	 * <p>The descriptor is like the bytecode form but is slightly easier to work with.
 	 * It does not include the trailing semicolon (for non array reference types).
 	 * Some examples: Ljava/lang/String, I, [I
-     */
+	 */
 	@Nullable
 	protected volatile String exitTypeDescriptor;
 
@@ -83,8 +85,8 @@ public abstract class SpelNodeImpl implements SpelNode, Opcodes {
 
 
 	/**
-     * Return {@code true} if the next child is one of the specified classes.
-     */
+	 * Return {@code true} if the next child is one of the specified classes.
+	 */
 	protected boolean nextChildIs(Class<?>... classes) {
 		if (this.parent != null) {
 			SpelNodeImpl[] peers = this.parent.children;
@@ -125,6 +127,28 @@ public abstract class SpelNodeImpl implements SpelNode, Opcodes {
 
 	@Override
 	public void setValue(ExpressionState expressionState, @Nullable Object newValue) throws EvaluationException {
+		setValueInternal(expressionState, () -> new TypedValue(newValue));
+	}
+
+	/**
+	 * Evaluate the expression to a node and then set the new value created by the
+	 * specified {@link Supplier} on that node.
+	 * <p>For example, if the expression evaluates to a property reference, then the
+	 * property will be set to the new value.
+	 * <p>Favor this method over {@link #setValue(ExpressionState, Object)} when
+	 * the value should be lazily computed.
+	 * <p>By default, this method throws a {@link SpelEvaluationException},
+	 * effectively disabling this feature. Subclasses may override this method to
+	 * provide an actual implementation.
+	 * @param expressionState the current expression state (includes the context)
+	 * @param valueSupplier a supplier of the new value
+	 * @throws EvaluationException if any problem occurs evaluating the expression or
+	 * setting the new value
+	 * @since 5.2.24
+	 */
+	public TypedValue setValueInternal(ExpressionState expressionState, Supplier<TypedValue> valueSupplier)
+			throws EvaluationException {
+
 		throw new SpelEvaluationException(getStartPosition(), SpelMessage.SETVALUE_NOT_SUPPORTED, getClass());
 	}
 

spring-expression/src/main/java/org/springframework/expression/spel/ast/VariableReference.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,9 +17,11 @@
 package org.springframework.expression.spel.ast;
 
 import java.lang.reflect.Modifier;
+import java.util.function.Supplier;
 
 import org.springframework.asm.MethodVisitor;
 import org.springframework.expression.EvaluationContext;
+import org.springframework.expression.EvaluationException;
 import org.springframework.expression.TypedValue;
 import org.springframework.expression.spel.CodeFlow;
 import org.springframework.expression.spel.ExpressionState;
@@ -27,10 +29,11 @@ import org.springframework.expression.spel.SpelEvaluationException;
 import org.springframework.lang.Nullable;
 
 /**
- * Represents a variable reference, eg. #someVar. Note this is different to a *local*
- * variable like $someVar
+ * Represents a variable reference — for example, {@code #someVar}. Note
+ * that this is different than a <em>local</em> variable like {@code $someVar}.
  *
  * @author Andy Clement
+ * @author Sam Brannen
  * @since 3.0
  */
 public class VariableReference extends SpelNodeImpl {
@@ -53,14 +56,14 @@ public class VariableReference extends SpelNodeImpl {
 	@Override
 	public ValueRef getValueRef(ExpressionState state) throws SpelEvaluationException {
 		if (this.name.equals(THIS)) {
-			return new ValueRef.TypedValueHolderValueRef(state.getActiveContextObject(),this);
+			return new ValueRef.TypedValueHolderValueRef(state.getActiveContextObject(), this);
 		}
 		if (this.name.equals(ROOT)) {
-			return new ValueRef.TypedValueHolderValueRef(state.getRootContextObject(),this);
+			return new ValueRef.TypedValueHolderValueRef(state.getRootContextObject(), this);
 		}
 		TypedValue result = state.lookupVariable(this.name);
 		// a null value will mean either the value was null or the variable was not found
-		return new VariableRef(this.name,result,state.getEvaluationContext());
+		return new VariableRef(this.name, result, state.getEvaluationContext());
 	}
 
 	@Override
@@ -90,8 +93,10 @@ public class VariableReference extends SpelNodeImpl {
 	}
 
 	@Override
-	public void setValue(ExpressionState state, @Nullable Object value) throws SpelEvaluationException {
-		state.setVariable(this.name, value);
+	public TypedValue setValueInternal(ExpressionState state, Supplier<TypedValue> valueSupplier)
+			throws EvaluationException {
+
+		return state.assignVariable(this.name, valueSupplier);
 	}
 
 	@Override

spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java

@@ -29,6 +29,7 @@ import org.springframework.expression.ParseException;
 import org.springframework.expression.ParserContext;
 import org.springframework.expression.common.TemplateAwareExpressionParser;
 import org.springframework.expression.spel.InternalParseException;
+import org.springframework.expression.spel.SpelEvaluationException;
 import org.springframework.expression.spel.SpelMessage;
 import org.springframework.expression.spel.SpelParseException;
 import org.springframework.expression.spel.SpelParserConfiguration;
@@ -92,7 +93,6 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 
 	private static final Pattern VALID_QUALIFIED_ID_PATTERN = Pattern.compile("[\\p{L}\\p{N}_$]+");
 
-
 	private final SpelParserConfiguration configuration;
 
 	// For rules that build nodes, they are stacked here for return
@@ -127,6 +127,8 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 	protected SpelExpression doParseExpression(String expressionString, @Nullable ParserContext context)
 			throws ParseException {
 
+		checkExpressionLength(expressionString);
+
 		try {
 			this.expressionString = expressionString;
 			Tokenizer tokenizer = new Tokenizer(expressionString);
@@ -148,6 +150,13 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 		}
 	}
 
+	private void checkExpressionLength(String string) {
+		int maxLength = this.configuration.getMaximumExpressionLength();
+		if (string.length() > maxLength) {
+			throw new SpelEvaluationException(SpelMessage.MAX_EXPRESSION_LENGTH_EXCEEDED, maxLength);
+		}
+	}
+
 	//	expression
 	//    : logicalOrExpression
 	//      ( (ASSIGN^ logicalOrExpression)

spring-expression/src/main/java/org/springframework/expression/spel/standard/SpelExpressionParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,6 +28,7 @@ import org.springframework.util.Assert;
  *
  * @author Andy Clement
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @since 3.0
  */
 public class SpelExpressionParser extends TemplateAwareExpressionParser {
@@ -53,6 +54,7 @@ public class SpelExpressionParser extends TemplateAwareExpressionParser {
 
 
 	public SpelExpression parseRaw(String expressionString) throws ParseException {
+		Assert.hasText(expressionString, "'expressionString' must not be null or blank");
 		return doParseExpression(expressionString, null);
 	}
 

spring-expression/src/main/java/org/springframework/expression/spel/support/SimpleEvaluationContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.function.Supplier;
 
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.TypeDescriptor;
@@ -78,6 +79,7 @@ import org.springframework.lang.Nullable;
  *
  * @author Rossen Stoyanchev
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @since 4.3.15
  * @see #forPropertyAccessors
  * @see #forReadOnlyDataBinding()
@@ -200,6 +202,17 @@ public final class SimpleEvaluationContext implements EvaluationContext {
 		return this.operatorOverloader;
 	}
 
+	/**
+	 * {@code SimpleEvaluationContext} does not support variable assignment within
+	 * expressions.
+	 * @throws SpelEvaluationException with {@link SpelMessage#VARIABLE_ASSIGNMENT_NOT_SUPPORTED}
+	 * @since 5.2.24
+	 */
+	@Override
+	public TypedValue assignVariable(String name, Supplier<TypedValue> valueSupplier) {
+		throw new SpelEvaluationException(SpelMessage.VARIABLE_ASSIGNMENT_NOT_SUPPORTED, "#" + name);
+	}
+
 	@Override
 	public void setVariable(String name, @Nullable Object value) {
 		this.variables.put(name, value);

spring-expression/src/test/java/org/springframework/expression/spel/AbstractExpressionTests.java

@@ -164,6 +164,24 @@ public abstract class AbstractExpressionTests {
 	 */
 	protected void evaluateAndCheckError(String expression, Class<?> expectedReturnType, SpelMessage expectedMessage,
 			Object... otherProperties) {
+
+		evaluateAndCheckError(this.parser, expression, expectedReturnType, expectedMessage, otherProperties);
+	}
+
+	/**
+	 * Evaluate the specified expression and ensure the expected message comes out.
+	 * The message may have inserts and they will be checked if otherProperties is specified.
+	 * The first entry in otherProperties should always be the position.
+	 * @param parser the expression parser to use
+	 * @param expression the expression to evaluate
+	 * @param expectedReturnType ask the expression return value to be of this type if possible
+	 * ({@code null} indicates don't ask for conversion)
+	 * @param expectedMessage the expected message
+	 * @param otherProperties the expected inserts within the message
+	 */
+	protected void evaluateAndCheckError(ExpressionParser parser, String expression, Class<?> expectedReturnType, SpelMessage expectedMessage,
+			Object... otherProperties) {
+
 		assertThatExceptionOfType(SpelEvaluationException.class).isThrownBy(() -> {
 			Expression expr = parser.parseExpression(expression);
 			assertThat(expr).as("expression").isNotNull();

spring-expression/src/test/java/org/springframework/expression/spel/EvaluationTests.java

@@ -25,6 +25,8 @@ import java.util.Map;
 
 import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
 
 import org.springframework.expression.AccessException;
 import org.springframework.expression.BeanResolver;
@@ -36,6 +38,7 @@ import org.springframework.expression.MethodFilter;
 import org.springframework.expression.ParseException;
 import org.springframework.expression.spel.standard.SpelExpression;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.expression.spel.support.SimpleEvaluationContext;
 import org.springframework.expression.spel.support.StandardEvaluationContext;
 import org.springframework.expression.spel.support.StandardTypeLocator;
 import org.springframework.expression.spel.testresources.TestPerson;
@@ -60,6 +63,40 @@ class EvaluationTests extends AbstractExpressionTests {
 	@Nested
 	class MiscellaneousTests {
 
+		@Test
+		void expressionLength() {
+			String expression = String.format("'X' + '%s'", repeat(" ", 9_992));
+			assertThat(expression).hasSize(10_000);
+			Expression expr = parser.parseExpression(expression);
+			String result = expr.getValue(context, String.class);
+			assertThat(result).hasSize(9_993);
+			assertThat(result.trim()).isEqualTo("X");
+
+			expression = String.format("'X' + '%s'", repeat(" ", 9_993));
+			assertThat(expression).hasSize(10_001);
+			evaluateAndCheckError(expression, String.class, SpelMessage.MAX_EXPRESSION_LENGTH_EXCEEDED);
+		}
+
+		@Test
+		void maxExpressionLengthIsConfigurable() {
+			int maximumExpressionLength = 20_000;
+
+			String expression = String.format("'%s'", repeat("Y", 19_998));
+			assertThat(expression).hasSize(maximumExpressionLength);
+
+			SpelParserConfiguration configuration =
+					new SpelParserConfiguration(null, null, false, false, 0, maximumExpressionLength);
+			ExpressionParser parser = new SpelExpressionParser(configuration);
+
+			Expression expr = parser.parseExpression(expression);
+			String result = expr.getValue(String.class);
+			assertThat(result).hasSize(19_998);
+
+			expression = String.format("'%s'", repeat("Y", 25_000));
+			assertThat(expression).hasSize(25_002);
+			evaluateAndCheckError(parser, expression, String.class, SpelMessage.MAX_EXPRESSION_LENGTH_EXCEEDED);
+		}
+
 		@Test
 		void createListsOnAttemptToIndexNull01() throws EvaluationException, ParseException {
 			ExpressionParser parser = new SpelExpressionParser(new SpelParserConfiguration(true, true));
@@ -135,8 +172,24 @@ class EvaluationTests extends AbstractExpressionTests {
 
 		// assignment
 		@Test
-		void assignmentToVariables() {
-			evaluate("#var1='value1'", "value1", String.class);
+		void assignmentToVariableWithStandardEvaluationContext() {
+			evaluate("#var1 = 'value1'", "value1", String.class);
+		}
+
+		@ParameterizedTest
+		@CsvSource(delimiterString = "->", value = {
+			"'#var1 = \"value1\"'    -> #var1",
+			"'true ? #myVar = 4 : 0' -> #myVar"
+		})
+		void assignmentToVariableWithSimpleEvaluationContext(String expression, String varName) {
+			EvaluationContext context = SimpleEvaluationContext.forReadWriteDataBinding().build();
+			Expression expr = parser.parseExpression(expression);
+			assertThatExceptionOfType(SpelEvaluationException.class)
+				.isThrownBy(() -> expr.getValue(context))
+				.satisfies(ex -> {
+					assertThat(ex.getMessageCode()).isEqualTo(SpelMessage.VARIABLE_ASSIGNMENT_NOT_SUPPORTED);
+					assertThat(ex.getInserts()).as("inserts").containsExactly(varName);
+				});
 		}
 
 		@Test
@@ -482,15 +535,13 @@ class EvaluationTests extends AbstractExpressionTests {
 
 		@Test
 		void matchesWithPatternLengthThreshold() {
-			String pattern = "(0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789" +
-					"0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789" +
-					"01234567890123456789012345678901234567890123456789|abc)";
-			assertThat(pattern).hasSize(256);
-			Expression expr = parser.parseExpression("'abc' matches '" + pattern + "'");
+			String pattern = String.format("^(%s|X)", repeat("12345", 199));
+			assertThat(pattern).hasSize(1000);
+			Expression expr = parser.parseExpression("'X' matches '" + pattern + "'");
 			assertThat(expr.getValue(context, Boolean.class)).isTrue();
 
 			pattern += "?";
-			assertThat(pattern).hasSize(257);
+			assertThat(pattern).hasSize(1001);
 			evaluateAndCheckError("'abc' matches '" + pattern + "'", Boolean.class, SpelMessage.MAX_REGEX_LENGTH_EXCEEDED);
 		}
 
@@ -1468,6 +1519,15 @@ class EvaluationTests extends AbstractExpressionTests {
 	}
 
 
+	private static String repeat(String str, int count) {
+		String result = "";
+		for (int i = 0; i < count; i++) {
+			result += str;
+		}
+		return result;
+	}
+
+
 	@SuppressWarnings("rawtypes")
 	static class TestClass {
 

spring-expression/src/test/java/org/springframework/expression/spel/OperatorTests.java

@@ -26,6 +26,7 @@ import org.springframework.expression.spel.ast.Operator;
 import org.springframework.expression.spel.standard.SpelExpression;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.expression.spel.SpelMessage.MAX_CONCATENATED_STRING_LENGTH_EXCEEDED;
 import static org.springframework.expression.spel.SpelMessage.MAX_REPEATED_TEXT_SIZE_EXCEEDED;
 
 /**
@@ -391,11 +392,7 @@ class OperatorTests extends AbstractExpressionTests {
 		evaluate("3.0f + 5.0f", 8.0f, Float.class);
 		evaluate("3.0d + 5.0d", 8.0d, Double.class);
 		evaluate("3 + new java.math.BigDecimal('5')", new BigDecimal("8"), BigDecimal.class);
-
-		evaluate("'ab' + 2", "ab2", String.class);
-		evaluate("2 + 'a'", "2a", String.class);
-		evaluate("'ab' + null", "abnull", String.class);
-		evaluate("null + 'ab'", "nullab", String.class);
+		evaluate("5 + new Integer('37')", 42, Integer.class);
 
 		// AST:
 		SpelExpression expr = (SpelExpression) parser.parseExpression("+3");
@@ -409,11 +406,6 @@ class OperatorTests extends AbstractExpressionTests {
 		evaluate("+5", 5, Integer.class);
 		evaluate("+new java.math.BigDecimal('5')", new BigDecimal("5"), BigDecimal.class);
 		evaluateAndCheckError("+'abc'", SpelMessage.OPERATOR_NOT_SUPPORTED_BETWEEN_TYPES);
-
-		// string concatenation
-		evaluate("'abc'+'def'", "abcdef", String.class);
-
-		evaluate("5 + new Integer('37')", 42, Integer.class);
 	}
 
 	@Test
@@ -587,6 +579,59 @@ class OperatorTests extends AbstractExpressionTests {
 		evaluateAndCheckError("'a' * 257", String.class, MAX_REPEATED_TEXT_SIZE_EXCEEDED, 4);
 	}
 
+	@Test
+	void stringConcatenation() {
+		evaluate("'' + ''", "", String.class);
+		evaluate("'' + null", "null", String.class);
+		evaluate("null + ''", "null", String.class);
+		evaluate("'ab' + null", "abnull", String.class);
+		evaluate("null + 'ab'", "nullab", String.class);
+		evaluate("'ab' + 2", "ab2", String.class);
+		evaluate("2 + 'ab'", "2ab", String.class);
+		evaluate("'abc' + 'def'", "abcdef", String.class);
+
+		// Text is big but not too big
+		final int maxSize = 100_000;
+		context.setVariable("text1", createString(maxSize));
+		Expression expr = parser.parseExpression("#text1 + ''");
+		assertThat(expr.getValue(context, String.class)).hasSize(maxSize);
+
+		expr = parser.parseExpression("'' + #text1");
+		assertThat(expr.getValue(context, String.class)).hasSize(maxSize);
+
+		context.setVariable("text1", createString(maxSize / 2));
+		expr = parser.parseExpression("#text1 + #text1");
+		assertThat(expr.getValue(context, String.class)).hasSize(maxSize);
+
+		// Text is too big
+		context.setVariable("text1", createString(maxSize + 1));
+		evaluateAndCheckError("#text1 + ''", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 7);
+		evaluateAndCheckError("#text1 + true", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 7);
+		evaluateAndCheckError("'' + #text1", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 3);
+		evaluateAndCheckError("true + #text1", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 5);
+
+		context.setVariable("text1", createString(maxSize / 2));
+		context.setVariable("text2", createString((maxSize / 2) + 1));
+		evaluateAndCheckError("#text1 + #text2", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 7);
+		evaluateAndCheckError("#text1 + #text2 + true", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 7);
+		evaluateAndCheckError("#text1 + true + #text2", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 14);
+		evaluateAndCheckError("true + #text1 + #text2", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 14);
+
+		evaluateAndCheckError("#text2 + #text1", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 7);
+		evaluateAndCheckError("#text2 + #text1 + true", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 7);
+		evaluateAndCheckError("#text2 + true + #text1", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 14);
+		evaluateAndCheckError("true + #text2 + #text1", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 14);
+
+		context.setVariable("text1", createString((maxSize / 3) + 1));
+		evaluateAndCheckError("#text1 + #text1 + #text1", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 16);
+		evaluateAndCheckError("(#text1 + #text1) + #text1", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 18);
+		evaluateAndCheckError("#text1 + (#text1 + #text1)", String.class, MAX_CONCATENATED_STRING_LENGTH_EXCEEDED, 7);
+	}
+
+	private static String createString(int size) {
+		return new String(new char[size]);
+	}
+
 	@Test
 	void longs() {
 		evaluate("3L == 4L", false, Boolean.class);

spring-expression/src/test/java/org/springframework/expression/spel/TemplateExpressionParsingTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,14 +30,16 @@ import org.springframework.expression.spel.support.StandardEvaluationContext;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 
 /**
  * @author Andy Clement
  * @author Juergen Hoeller
+ * @author Sam Brannen
  */
-public class TemplateExpressionParsingTests extends AbstractExpressionTests {
+class TemplateExpressionParsingTests extends AbstractExpressionTests {
 
-	public static final ParserContext DEFAULT_TEMPLATE_PARSER_CONTEXT = new ParserContext() {
+	static final ParserContext DEFAULT_TEMPLATE_PARSER_CONTEXT = new ParserContext() {
 		@Override
 		public String getExpressionPrefix() {
 			return "${";
@@ -52,7 +54,7 @@ public class TemplateExpressionParsingTests extends AbstractExpressionTests {
 		}
 	};
 
-	public static final ParserContext HASH_DELIMITED_PARSER_CONTEXT = new ParserContext() {
+	static final ParserContext HASH_DELIMITED_PARSER_CONTEXT = new ParserContext() {
 		@Override
 		public String getExpressionPrefix() {
 			return "#{";
@@ -68,25 +70,32 @@ public class TemplateExpressionParsingTests extends AbstractExpressionTests {
 	};
 
 
+	private final SpelExpressionParser parser = new SpelExpressionParser();
+
+
 	@Test
-	public void testParsingSimpleTemplateExpression01() throws Exception {
-		SpelExpressionParser parser = new SpelExpressionParser();
+	void nullTemplateExpressionIsRejected() {
+		assertThatIllegalArgumentException()
+			.isThrownBy(() -> parser.parseExpression(null, DEFAULT_TEMPLATE_PARSER_CONTEXT))
+			.withMessage("'expressionString' must not be null");
+	}
+
+	@Test
+	void parsingSimpleTemplateExpression01() {
 		Expression expr = parser.parseExpression("hello ${'world'}", DEFAULT_TEMPLATE_PARSER_CONTEXT);
 		Object o = expr.getValue();
 		assertThat(o.toString()).isEqualTo("hello world");
 	}
 
 	@Test
-	public void testParsingSimpleTemplateExpression02() throws Exception {
-		SpelExpressionParser parser = new SpelExpressionParser();
+	void parsingSimpleTemplateExpression02() {
 		Expression expr = parser.parseExpression("hello ${'to'} you", DEFAULT_TEMPLATE_PARSER_CONTEXT);
 		Object o = expr.getValue();
 		assertThat(o.toString()).isEqualTo("hello to you");
 	}
 
 	@Test
-	public void testParsingSimpleTemplateExpression03() throws Exception {
-		SpelExpressionParser parser = new SpelExpressionParser();
+	void parsingSimpleTemplateExpression03() {
 		Expression expr = parser.parseExpression("The quick ${'brown'} fox jumped over the ${'lazy'} dog",
 				DEFAULT_TEMPLATE_PARSER_CONTEXT);
 		Object o = expr.getValue();
@@ -94,8 +103,7 @@ public class TemplateExpressionParsingTests extends AbstractExpressionTests {
 	}
 
 	@Test
-	public void testParsingSimpleTemplateExpression04() throws Exception {
-		SpelExpressionParser parser = new SpelExpressionParser();
+	void parsingSimpleTemplateExpression04() {
 		Expression expr = parser.parseExpression("${'hello'} world", DEFAULT_TEMPLATE_PARSER_CONTEXT);
 		Object o = expr.getValue();
 		assertThat(o.toString()).isEqualTo("hello world");
@@ -114,8 +122,7 @@ public class TemplateExpressionParsingTests extends AbstractExpressionTests {
 	}
 
 	@Test
-	public void testCompositeStringExpression() throws Exception {
-		SpelExpressionParser parser = new SpelExpressionParser();
+	void compositeStringExpression() {
 		Expression ex = parser.parseExpression("hello ${'world'}", DEFAULT_TEMPLATE_PARSER_CONTEXT);
 		assertThat(ex.getValue()).isInstanceOf(String.class).isEqualTo("hello world");
 		assertThat(ex.getValue(String.class)).isInstanceOf(String.class).isEqualTo("hello world");
@@ -154,8 +161,7 @@ public class TemplateExpressionParsingTests extends AbstractExpressionTests {
 	static class Rooty {}
 
 	@Test
-	public void testNestedExpressions() throws Exception {
-		SpelExpressionParser parser = new SpelExpressionParser();
+	void nestedExpressions() {
 		// treat the nested ${..} as a part of the expression
 		Expression ex = parser.parseExpression("hello ${listOfNumbersUpToTen.$[#this<5]} world",DEFAULT_TEMPLATE_PARSER_CONTEXT);
 		String s = ex.getValue(TestScenarioCreator.getTestEvaluationContext(),String.class);
@@ -185,8 +191,7 @@ public class TemplateExpressionParsingTests extends AbstractExpressionTests {
 	}
 
 	@Test
-
-	public void testClashingWithSuffixes() throws Exception {
+	void clashingWithSuffixes() {
 		// Just wanting to use the prefix or suffix within the template:
 		Expression ex = parser.parseExpression("hello ${3+4} world",DEFAULT_TEMPLATE_PARSER_CONTEXT);
 		String s = ex.getValue(TestScenarioCreator.getTestEvaluationContext(),String.class);
@@ -202,13 +207,13 @@ public class TemplateExpressionParsingTests extends AbstractExpressionTests {
 	}
 
 	@Test
-	public void testParsingNormalExpressionThroughTemplateParser() throws Exception {
+	void parsingNormalExpressionThroughTemplateParser() {
 		Expression expr = parser.parseExpression("1+2+3");
 		assertThat(expr.getValue()).isEqualTo(6);
 	}
 
 	@Test
-	public void testErrorCases() throws Exception {
+	void errorCases() {
 		assertThatExceptionOfType(ParseException.class).isThrownBy(() ->
 				parser.parseExpression("hello ${'world'", DEFAULT_TEMPLATE_PARSER_CONTEXT))
 			.satisfies(pex -> {
@@ -224,7 +229,7 @@ public class TemplateExpressionParsingTests extends AbstractExpressionTests {
 	}
 
 	@Test
-	public void testTemplateParserContext() {
+	void testTemplateParserContext() {
 		TemplateParserContext tpc = new TemplateParserContext("abc","def");
 		assertThat(tpc.getExpressionPrefix()).isEqualTo("abc");
 		assertThat(tpc.getExpressionSuffix()).isEqualTo("def");

spring-expression/src/test/java/org/springframework/expression/spel/standard/SpelParserTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,8 @@ package org.springframework.expression.spel.standard;
 
 import java.util.function.Consumer;
 
+import org.assertj.core.api.ThrowableAssert.ThrowingCallable;
+import org.assertj.core.api.ThrowableAssertAlternative;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.expression.EvaluationContext;
@@ -31,16 +33,55 @@ import org.springframework.expression.spel.support.StandardEvaluationContext;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+import static org.springframework.expression.spel.SpelMessage.MISSING_CONSTRUCTOR_ARGS;
+import static org.springframework.expression.spel.SpelMessage.NON_TERMINATING_DOUBLE_QUOTED_STRING;
+import static org.springframework.expression.spel.SpelMessage.NON_TERMINATING_QUOTED_STRING;
+import static org.springframework.expression.spel.SpelMessage.NOT_AN_INTEGER;
+import static org.springframework.expression.spel.SpelMessage.NOT_A_LONG;
+import static org.springframework.expression.spel.SpelMessage.REAL_CANNOT_BE_LONG;
+import static org.springframework.expression.spel.SpelMessage.RUN_OUT_OF_ARGUMENTS;
+import static org.springframework.expression.spel.SpelMessage.UNEXPECTED_DATA_AFTER_DOT;
+import static org.springframework.expression.spel.SpelMessage.UNEXPECTED_ESCAPE_CHAR;
 
 /**
  * @author Andy Clement
  * @author Juergen Hoeller
+ * @author Sam Brannen
  */
 class SpelParserTests {
 
+	private final SpelExpressionParser parser = new SpelExpressionParser();
+
+
+	@Test
+	void nullExpressionIsRejected() {
+		assertNullOrEmptyExpressionIsRejected(() -> parser.parseExpression(null));
+		assertNullOrEmptyExpressionIsRejected(() -> parser.parseRaw(null));
+	}
+
+	@Test
+	void emptyExpressionIsRejected() {
+		assertNullOrEmptyExpressionIsRejected(() -> parser.parseExpression(""));
+		assertNullOrEmptyExpressionIsRejected(() -> parser.parseRaw(""));
+	}
+
+	@Test
+	void blankExpressionIsRejected() {
+		assertNullOrEmptyExpressionIsRejected(() -> parser.parseExpression("     "));
+		assertNullOrEmptyExpressionIsRejected(() -> parser.parseExpression("\t\n"));
+		assertNullOrEmptyExpressionIsRejected(() -> parser.parseRaw("     "));
+		assertNullOrEmptyExpressionIsRejected(() -> parser.parseRaw("\t\n"));
+	}
+
+	private static void assertNullOrEmptyExpressionIsRejected(ThrowingCallable throwingCallable) {
+		assertThatIllegalArgumentException()
+			.isThrownBy(throwingCallable)
+			.withMessage("'expressionString' must not be null or blank");
+	}
+
 	@Test
 	void theMostBasic() {
-		SpelExpressionParser parser = new SpelExpressionParser();
 		SpelExpression expr = parser.parseRaw("2");
 		assertThat(expr).isNotNull();
 		assertThat(expr.getAST()).isNotNull();
@@ -51,7 +92,6 @@ class SpelParserTests {
 
 	@Test
 	void valueType() {
-		SpelExpressionParser parser = new SpelExpressionParser();
 		EvaluationContext ctx = new StandardEvaluationContext();
 		Class<?> c = parser.parseRaw("2").getValueType();
 		assertThat(c).isEqualTo(Integer.class);
@@ -67,7 +107,6 @@ class SpelParserTests {
 
 	@Test
 	void whitespace() {
-		SpelExpressionParser parser = new SpelExpressionParser();
 		SpelExpression expr = parser.parseRaw("2      +    3");
 		assertThat(expr.getValue()).isEqualTo(5);
 		expr = parser.parseRaw("2	+	3");
@@ -80,7 +119,6 @@ class SpelParserTests {
 
 	@Test
 	void arithmeticPlus1() {
-		SpelExpressionParser parser = new SpelExpressionParser();
 		SpelExpression expr = parser.parseRaw("2+2");
 		assertThat(expr).isNotNull();
 		assertThat(expr.getAST()).isNotNull();
@@ -89,14 +127,12 @@ class SpelParserTests {
 
 	@Test
 	void arithmeticPlus2() {
-		SpelExpressionParser parser = new SpelExpressionParser();
 		SpelExpression expr = parser.parseRaw("37+41");
 		assertThat(expr.getValue()).isEqualTo(78);
 	}
 
 	@Test
 	void arithmeticMultiply1() {
-		SpelExpressionParser parser = new SpelExpressionParser();
 		SpelExpression expr = parser.parseRaw("2*3");
 		assertThat(expr).isNotNull();
 		assertThat(expr.getAST()).isNotNull();
@@ -105,162 +141,120 @@ class SpelParserTests {
 
 	@Test
 	void arithmeticPrecedence1() {
-		SpelExpressionParser parser = new SpelExpressionParser();
 		SpelExpression expr = parser.parseRaw("2*3+5");
 		assertThat(expr.getValue()).isEqualTo(11);
 	}
 
 	@Test
-	void generalExpressions() {
-		assertThatExceptionOfType(SpelParseException.class).isThrownBy(() -> {
-			SpelExpressionParser parser = new SpelExpressionParser();
-			parser.parseRaw("new String");
-		})
-		.satisfies(parseExceptionRequirements(SpelMessage.MISSING_CONSTRUCTOR_ARGS, 10));
-
-		assertThatExceptionOfType(SpelParseException.class).isThrownBy(() -> {
-			SpelExpressionParser parser = new SpelExpressionParser();
-			parser.parseRaw("new String(3,");
-		})
-		.satisfies(parseExceptionRequirements(SpelMessage.RUN_OUT_OF_ARGUMENTS, 10));
-
-		assertThatExceptionOfType(SpelParseException.class).isThrownBy(() -> {
-			SpelExpressionParser parser = new SpelExpressionParser();
-			parser.parseRaw("new String(3");
-		})
-		.satisfies(parseExceptionRequirements(SpelMessage.RUN_OUT_OF_ARGUMENTS, 10));
-
-		assertThatExceptionOfType(SpelParseException.class).isThrownBy(() -> {
-			SpelExpressionParser parser = new SpelExpressionParser();
-			parser.parseRaw("new String(");
-		})
-		.satisfies(parseExceptionRequirements(SpelMessage.RUN_OUT_OF_ARGUMENTS, 10));
-
-		assertThatExceptionOfType(SpelParseException.class).isThrownBy(() -> {
-			SpelExpressionParser parser = new SpelExpressionParser();
-			parser.parseRaw("\"abc");
-		})
-		.satisfies(parseExceptionRequirements(SpelMessage.NON_TERMINATING_DOUBLE_QUOTED_STRING, 0));
-
-		assertThatExceptionOfType(SpelParseException.class).isThrownBy(() -> {
-			SpelExpressionParser parser = new SpelExpressionParser();
-			parser.parseRaw("'abc");
-		})
-		.satisfies(parseExceptionRequirements(SpelMessage.NON_TERMINATING_QUOTED_STRING, 0));
-
-	}
-
-	private <E extends SpelParseException> Consumer<E> parseExceptionRequirements(
-			SpelMessage expectedMessage, int expectedPosition) {
-		return ex -> {
-			assertThat(ex.getMessageCode()).isEqualTo(expectedMessage);
-			assertThat(ex.getPosition()).isEqualTo(expectedPosition);
-			assertThat(ex.getMessage()).contains(ex.getExpressionString());
-		};
+	void parseExceptions() {
+		assertParseException(() -> parser.parseRaw("new String"), MISSING_CONSTRUCTOR_ARGS, 10);
+		assertParseException(() -> parser.parseRaw("new String(3,"), RUN_OUT_OF_ARGUMENTS, 10);
+		assertParseException(() -> parser.parseRaw("new String(3"), RUN_OUT_OF_ARGUMENTS, 10);
+		assertParseException(() -> parser.parseRaw("new String("), RUN_OUT_OF_ARGUMENTS, 10);
+		assertParseException(() -> parser.parseRaw("\"abc"), NON_TERMINATING_DOUBLE_QUOTED_STRING, 0);
+		assertParseException(() -> parser.parseRaw("'abc"), NON_TERMINATING_QUOTED_STRING, 0);
 	}
 
 	@Test
 	void arithmeticPrecedence2() {
-		SpelExpressionParser parser = new SpelExpressionParser();
 		SpelExpression expr = parser.parseRaw("2+3*5");
 		assertThat(expr.getValue()).isEqualTo(17);
 	}
 
 	@Test
 	void arithmeticPrecedence3() {
-		SpelExpression expr = new SpelExpressionParser().parseRaw("3+10/2");
+		SpelExpression expr = parser.parseRaw("3+10/2");
 		assertThat(expr.getValue()).isEqualTo(8);
 	}
 
 	@Test
 	void arithmeticPrecedence4() {
-		SpelExpression expr = new SpelExpressionParser().parseRaw("10/2+3");
+		SpelExpression expr = parser.parseRaw("10/2+3");
 		assertThat(expr.getValue()).isEqualTo(8);
 	}
 
 	@Test
 	void arithmeticPrecedence5() {
-		SpelExpression expr = new SpelExpressionParser().parseRaw("(4+10)/2");
+		SpelExpression expr = parser.parseRaw("(4+10)/2");
 		assertThat(expr.getValue()).isEqualTo(7);
 	}
 
 	@Test
 	void arithmeticPrecedence6() {
-		SpelExpression expr = new SpelExpressionParser().parseRaw("(3+2)*2");
+		SpelExpression expr = parser.parseRaw("(3+2)*2");
 		assertThat(expr.getValue()).isEqualTo(10);
 	}
 
 	@Test
 	void booleanOperators() {
-		SpelExpression expr = new SpelExpressionParser().parseRaw("true");
-		assertThat(expr.getValue(Boolean.class)).isEqualTo(Boolean.TRUE);
-		expr = new SpelExpressionParser().parseRaw("false");
-		assertThat(expr.getValue(Boolean.class)).isEqualTo(Boolean.FALSE);
-		expr = new SpelExpressionParser().parseRaw("false and false");
-		assertThat(expr.getValue(Boolean.class)).isEqualTo(Boolean.FALSE);
-		expr = new SpelExpressionParser().parseRaw("true and (true or false)");
-		assertThat(expr.getValue(Boolean.class)).isEqualTo(Boolean.TRUE);
-		expr = new SpelExpressionParser().parseRaw("true and true or false");
-		assertThat(expr.getValue(Boolean.class)).isEqualTo(Boolean.TRUE);
-		expr = new SpelExpressionParser().parseRaw("!true");
-		assertThat(expr.getValue(Boolean.class)).isEqualTo(Boolean.FALSE);
-		expr = new SpelExpressionParser().parseRaw("!(false or true)");
-		assertThat(expr.getValue(Boolean.class)).isEqualTo(Boolean.FALSE);
+		SpelExpression expr = parser.parseRaw("true");
+		assertThat(expr.getValue(Boolean.class)).isTrue();
+		expr = parser.parseRaw("false");
+		assertThat(expr.getValue(Boolean.class)).isFalse();
+		expr = parser.parseRaw("false and false");
+		assertThat(expr.getValue(Boolean.class)).isFalse();
+		expr = parser.parseRaw("true and (true or false)");
+		assertThat(expr.getValue(Boolean.class)).isTrue();
+		expr = parser.parseRaw("true and true or false");
+		assertThat(expr.getValue(Boolean.class)).isTrue();
+		expr = parser.parseRaw("!true");
+		assertThat(expr.getValue(Boolean.class)).isFalse();
+		expr = parser.parseRaw("!(false or true)");
+		assertThat(expr.getValue(Boolean.class)).isFalse();
 	}
 
 	@Test
 	void booleanOperators_symbolic_spr9614() {
-		SpelExpression expr = new SpelExpressionParser().parseRaw("true");
-		assertThat(expr.getValue(Boolean.class)).isEqualTo(Boolean.TRUE);
-		expr = new SpelExpressionParser().parseRaw("false");
-		assertThat(expr.getValue(Boolean.class)).isEqualTo(Boolean.FALSE);
-		expr = new SpelExpressionParser().parseRaw("false && false");
-		assertThat(expr.getValue(Boolean.class)).isEqualTo(Boolean.FALSE);
-		expr = new SpelExpressionParser().parseRaw("true && (true || false)");
-		assertThat(expr.getValue(Boolean.class)).isEqualTo(Boolean.TRUE);
-		expr = new SpelExpressionParser().parseRaw("true && true || false");
-		assertThat(expr.getValue(Boolean.class)).isEqualTo(Boolean.TRUE);
-		expr = new SpelExpressionParser().parseRaw("!true");
-		assertThat(expr.getValue(Boolean.class)).isEqualTo(Boolean.FALSE);
-		expr = new SpelExpressionParser().parseRaw("!(false || true)");
-		assertThat(expr.getValue(Boolean.class)).isEqualTo(Boolean.FALSE);
+		SpelExpression expr = parser.parseRaw("true");
+		assertThat(expr.getValue(Boolean.class)).isTrue();
+		expr = parser.parseRaw("false");
+		assertThat(expr.getValue(Boolean.class)).isFalse();
+		expr = parser.parseRaw("false && false");
+		assertThat(expr.getValue(Boolean.class)).isFalse();
+		expr = parser.parseRaw("true && (true || false)");
+		assertThat(expr.getValue(Boolean.class)).isTrue();
+		expr = parser.parseRaw("true && true || false");
+		assertThat(expr.getValue(Boolean.class)).isTrue();
+		expr = parser.parseRaw("!true");
+		assertThat(expr.getValue(Boolean.class)).isFalse();
+		expr = parser.parseRaw("!(false || true)");
+		assertThat(expr.getValue(Boolean.class)).isFalse();
 	}
 
 	@Test
 	void stringLiterals() {
-		SpelExpression expr = new SpelExpressionParser().parseRaw("'howdy'");
+		SpelExpression expr = parser.parseRaw("'howdy'");
 		assertThat(expr.getValue()).isEqualTo("howdy");
-		expr = new SpelExpressionParser().parseRaw("'hello '' world'");
+		expr = parser.parseRaw("'hello '' world'");
 		assertThat(expr.getValue()).isEqualTo("hello ' world");
 	}
 
 	@Test
 	void stringLiterals2() {
-		SpelExpression expr = new SpelExpressionParser().parseRaw("'howdy'.substring(0,2)");
+		SpelExpression expr = parser.parseRaw("'howdy'.substring(0,2)");
 		assertThat(expr.getValue()).isEqualTo("ho");
 	}
 
 	@Test
 	void testStringLiterals_DoubleQuotes_spr9620() {
-		SpelExpression expr = new SpelExpressionParser().parseRaw("\"double quote: \"\".\"");
+		SpelExpression expr = parser.parseRaw("\"double quote: \"\".\"");
 		assertThat(expr.getValue()).isEqualTo("double quote: \".");
-		expr = new SpelExpressionParser().parseRaw("\"hello \"\" world\"");
+		expr = parser.parseRaw("\"hello \"\" world\"");
 		assertThat(expr.getValue()).isEqualTo("hello \" world");
 	}
 
 	@Test
 	void testStringLiterals_DoubleQuotes_spr9620_2() {
-		assertThatExceptionOfType(SpelParseException.class).isThrownBy(() ->
-				new SpelExpressionParser().parseRaw("\"double quote: \\\"\\\".\""))
+		assertParseExceptionThrownBy(() -> parser.parseRaw("\"double quote: \\\"\\\".\""))
 			.satisfies(ex -> {
 				assertThat(ex.getPosition()).isEqualTo(17);
-				assertThat(ex.getMessageCode()).isEqualTo(SpelMessage.UNEXPECTED_ESCAPE_CHAR);
+				assertThat(ex.getMessageCode()).isEqualTo(UNEXPECTED_ESCAPE_CHAR);
 			});
 	}
 
 	@Test
 	void positionalInformation() {
-		SpelExpression expr = new SpelExpressionParser().parseRaw("true and true or false");
+		SpelExpression expr = parser.parseRaw("true and true or false");
 		SpelNode rootAst = expr.getAST();
 		OpOr operatorOr = (OpOr) rootAst;
 		OpAnd operatorAnd = (OpAnd) operatorOr.getLeftOperand();
@@ -355,10 +349,10 @@ class SpelParserTests {
 		checkNumber("0xa", 10, Integer.class);
 		checkNumber("0xAL", 10L, Long.class);
 
-		checkNumberError("0x", SpelMessage.NOT_AN_INTEGER);
-		checkNumberError("0xL", SpelMessage.NOT_A_LONG);
-		checkNumberError(".324", SpelMessage.UNEXPECTED_DATA_AFTER_DOT);
-		checkNumberError("3.4L", SpelMessage.REAL_CANNOT_BE_LONG);
+		checkNumberError("0x", NOT_AN_INTEGER);
+		checkNumberError("0xL", NOT_A_LONG);
+		checkNumberError(".324", UNEXPECTED_DATA_AFTER_DOT);
+		checkNumberError("3.4L", REAL_CANNOT_BE_LONG);
 
 		checkNumber("3.5f", 3.5f, Float.class);
 		checkNumber("1.2e3", 1.2e3d, Double.class);
@@ -371,7 +365,6 @@ class SpelParserTests {
 
 	private void checkNumber(String expression, Object value, Class<?> type) {
 		try {
-			SpelExpressionParser parser = new SpelExpressionParser();
 			SpelExpression expr = parser.parseRaw(expression);
 			Object exprVal = expr.getValue();
 			assertThat(exprVal).isEqualTo(value);
@@ -383,9 +376,26 @@ class SpelParserTests {
 	}
 
 	private void checkNumberError(String expression, SpelMessage expectedMessage) {
-		SpelExpressionParser parser = new SpelExpressionParser();
-		assertThatExceptionOfType(SpelParseException.class).isThrownBy(() -> parser.parseRaw(expression))
+		assertParseExceptionThrownBy(() -> parser.parseRaw(expression))
 			.satisfies(ex -> assertThat(ex.getMessageCode()).isEqualTo(expectedMessage));
 	}
 
+	private static ThrowableAssertAlternative<SpelParseException> assertParseExceptionThrownBy(ThrowingCallable throwingCallable) {
+		return assertThatExceptionOfType(SpelParseException.class).isThrownBy(throwingCallable);
+	}
+
+	private static void assertParseException(ThrowingCallable throwingCallable, SpelMessage expectedMessage, int expectedPosition) {
+		assertParseExceptionThrownBy(throwingCallable)
+			.satisfies(parseExceptionRequirements(expectedMessage, expectedPosition));
+	}
+
+	private static <E extends SpelParseException> Consumer<E> parseExceptionRequirements(
+			SpelMessage expectedMessage, int expectedPosition) {
+		return ex -> {
+			assertThat(ex.getMessageCode()).isEqualTo(expectedMessage);
+			assertThat(ex.getPosition()).isEqualTo(expectedPosition);
+			assertThat(ex.getMessage()).contains(ex.getExpressionString());
+		};
+	}
+
 }

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/DataSourceTransactionManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,49 +35,52 @@ import org.springframework.transaction.support.TransactionSynchronizationUtils;
 import org.springframework.util.Assert;
 
 /**
- * {@link org.springframework.transaction.PlatformTransactionManager}
- * implementation for a single JDBC {@link javax.sql.DataSource}. This class is
- * capable of working in any environment with any JDBC driver, as long as the setup
- * uses a {@code javax.sql.DataSource} as its {@code Connection} factory mechanism.
- * Binds a JDBC Connection from the specified DataSource to the current thread,
- * potentially allowing for one thread-bound Connection per DataSource.
+ * {@link org.springframework.transaction.PlatformTransactionManager} implementation
+ * for a single JDBC {@link javax.sql.DataSource}. This class is capable of working
+ * in any environment with any JDBC driver, as long as the setup uses a
+ * {@code javax.sql.DataSource} as its {@code Connection} factory mechanism.
+ * Binds a JDBC {@code Connection} from the specified {@code DataSource} to the
+ * current thread, potentially allowing for one thread-bound {@code Connection}
+ * per {@code DataSource}.
  *
- * <p><b>Note: The DataSource that this transaction manager operates on needs
- * to return independent Connections.</b> The Connections may come from a pool
- * (the typical case), but the DataSource must not return thread-scoped /
- * request-scoped Connections or the like. This transaction manager will
- * associate Connections with thread-bound transactions itself, according
- * to the specified propagation behavior. It assumes that a separate,
- * independent Connection can be obtained even during an ongoing transaction.
+ * <p><b>Note: The {@code DataSource} that this transaction manager operates on
+ * needs to return independent {@code Connection}s.</b> The {@code Connection}s
+ * typically come from a connection pool but the {@code DataSource} must not return
+ * specifically scoped or constrained {@code Connection}s. This transaction manager
+ * will associate {@code Connection}s with thread-bound transactions, according
+ * to the specified propagation behavior. It assumes that a separate, independent
+ * {@code Connection} can be obtained even during an ongoing transaction.
  *
- * <p>Application code is required to retrieve the JDBC Connection via
+ * <p>Application code is required to retrieve the JDBC {@code Connection} via
  * {@link DataSourceUtils#getConnection(DataSource)} instead of a standard
- * Java EE-style {@link DataSource#getConnection()} call. Spring classes such as
+ * EE-style {@link DataSource#getConnection()} call. Spring classes such as
  * {@link org.springframework.jdbc.core.JdbcTemplate} use this strategy implicitly.
  * If not used in combination with this transaction manager, the
  * {@link DataSourceUtils} lookup strategy behaves exactly like the native
- * DataSource lookup; it can thus be used in a portable fashion.
+ * {@code DataSource} lookup; it can thus be used in a portable fashion.
  *
  * <p>Alternatively, you can allow application code to work with the standard
- * Java EE-style lookup pattern {@link DataSource#getConnection()}, for example for
- * legacy code that is not aware of Spring at all. In that case, define a
- * {@link TransactionAwareDataSourceProxy} for your target DataSource, and pass
- * that proxy DataSource to your DAOs, which will automatically participate in
- * Spring-managed transactions when accessing it.
+ * EE-style lookup pattern {@link DataSource#getConnection()}, for example
+ * for legacy code that is not aware of Spring at all. In that case, define a
+ * {@link TransactionAwareDataSourceProxy} for your target {@code DataSource},
+ * and pass that proxy {@code DataSource} to your DAOs which will automatically
+ * participate in Spring-managed transactions when accessing it.
  *
  * <p>Supports custom isolation levels, and timeouts which get applied as
  * appropriate JDBC statement timeouts. To support the latter, application code
  * must either use {@link org.springframework.jdbc.core.JdbcTemplate}, call
- * {@link DataSourceUtils#applyTransactionTimeout} for each created JDBC Statement,
- * or go through a {@link TransactionAwareDataSourceProxy} which will create
- * timeout-aware JDBC Connections and Statements automatically.
+ * {@link DataSourceUtils#applyTransactionTimeout} for each created JDBC
+ * {@code Statement}, or go through a {@link TransactionAwareDataSourceProxy}
+ * which will create timeout-aware JDBC {@code Connection}s and {@code Statement}s
+ * automatically.
  *
  * <p>Consider defining a {@link LazyConnectionDataSourceProxy} for your target
- * DataSource, pointing both this transaction manager and your DAOs to it.
+ * {@code DataSource}, pointing both this transaction manager and your DAOs to it.
  * This will lead to optimized handling of "empty" transactions, i.e. of transactions
- * without any JDBC statements executed. A LazyConnectionDataSourceProxy will not fetch
- * an actual JDBC Connection from the target DataSource until a Statement gets executed,
- * lazily applying the specified transaction settings to the target Connection.
+ * without any JDBC statements executed. A {@code LazyConnectionDataSourceProxy} will
+ * not fetch an actual JDBC {@code Connection} from the target {@code DataSource}
+ * until a {@code Statement} gets executed, lazily applying the specified transaction
+ * settings to the target {@code Connection}.
  *
  * <p>This transaction manager supports nested transactions via the JDBC 3.0
  * {@link java.sql.Savepoint} mechanism. The
@@ -88,9 +91,9 @@ import org.springframework.util.Assert;
  * <p>This transaction manager can be used as a replacement for the
  * {@link org.springframework.transaction.jta.JtaTransactionManager} in the single
  * resource case, as it does not require a container that supports JTA, typically
- * in combination with a locally defined JDBC DataSource (e.g. an Apache Commons
- * DBCP connection pool). Switching between this local strategy and a JTA
- * environment is just a matter of configuration!
+ * in combination with a locally defined JDBC {@code DataSource} (e.g. a Hikari
+ * connection pool). Switching between this local strategy and a JTA environment
+ * is just a matter of configuration!
  *
  * <p>As of 4.3.4, this transaction manager triggers flush callbacks on registered
  * transaction synchronizations (if synchronization is generally active), assuming
@@ -112,6 +115,7 @@ import org.springframework.util.Assert;
  * @see TransactionAwareDataSourceProxy
  * @see LazyConnectionDataSourceProxy
  * @see org.springframework.jdbc.core.JdbcTemplate
+ * @see org.springframework.jdbc.support.JdbcTransactionManager
  */
 @SuppressWarnings("serial")
 public class DataSourceTransactionManager extends AbstractPlatformTransactionManager
@@ -124,8 +128,8 @@ public class DataSourceTransactionManager extends AbstractPlatformTransactionMan
 
 
 	/**
-	 * Create a new DataSourceTransactionManager instance.
-	 * A DataSource has to be set to be able to use it.
+	 * Create a new {@code DataSourceTransactionManager} instance.
+	 * A {@code DataSource} has to be set to be able to use it.
 	 * @see #setDataSource
 	 */
 	public DataSourceTransactionManager() {
@@ -133,7 +137,7 @@ public class DataSourceTransactionManager extends AbstractPlatformTransactionMan
 	}
 
 	/**
-	 * Create a new DataSourceTransactionManager instance.
+	 * Create a new {@code DataSourceTransactionManager} instance.
 	 * @param dataSource the JDBC DataSource to manage transactions for
 	 */
 	public DataSourceTransactionManager(DataSource dataSource) {
@@ -144,22 +148,22 @@ public class DataSourceTransactionManager extends AbstractPlatformTransactionMan
 
 
 	/**
-	 * Set the JDBC DataSource that this instance should manage transactions for.
-	 * <p>This will typically be a locally defined DataSource, for example an
-	 * Apache Commons DBCP connection pool. Alternatively, you can also drive
-	 * transactions for a non-XA J2EE DataSource fetched from JNDI. For an XA
-	 * DataSource, use JtaTransactionManager.
-	 * <p>The DataSource specified here should be the target DataSource to manage
-	 * transactions for, not a TransactionAwareDataSourceProxy. Only data access
-	 * code may work with TransactionAwareDataSourceProxy, while the transaction
-	 * manager needs to work on the underlying target DataSource. If there's
-	 * nevertheless a TransactionAwareDataSourceProxy passed in, it will be
-	 * unwrapped to extract its target DataSource.
-	 * <p><b>The DataSource passed in here needs to return independent Connections.</b>
-	 * The Connections may come from a pool (the typical case), but the DataSource
-	 * must not return thread-scoped / request-scoped Connections or the like.
-	 * @see TransactionAwareDataSourceProxy
-	 * @see org.springframework.transaction.jta.JtaTransactionManager
+	 * Set the JDBC {@code DataSource} that this instance should manage transactions for.
+	 * <p>This will typically be a locally defined {@code DataSource}, for example a
+	 * Hikari connection pool. Alternatively, you can also manage transactions for a
+	 * non-XA {@code DataSource} fetched from JNDI. For an XA {@code DataSource},
+	 * use {@link org.springframework.transaction.jta.JtaTransactionManager} instead.
+	 * <p>The {@code DataSource} specified here should be the target {@code DataSource}
+	 * to manage transactions for, not a {@link TransactionAwareDataSourceProxy}.
+	 * Only data access code may work with {@code TransactionAwareDataSourceProxy} while
+	 * the transaction manager needs to work on the underlying target {@code DataSource}.
+	 * If there is nevertheless a {@code TransactionAwareDataSourceProxy} passed in,
+	 * it will be unwrapped to extract its target {@code DataSource}.
+	 * <p><b>The {@code DataSource} passed in here needs to return independent
+	 * {@code Connection}s.</b> The {@code Connection}s typically come from a
+	 * connection pool but the {@code DataSource} must not return specifically
+	 * scoped or constrained {@code Connection}s, just possibly lazily fetched.
+	 * @see LazyConnectionDataSourceProxy
 	 */
 	public void setDataSource(@Nullable DataSource dataSource) {
 		if (dataSource instanceof TransactionAwareDataSourceProxy) {
@@ -174,7 +178,7 @@ public class DataSourceTransactionManager extends AbstractPlatformTransactionMan
 	}
 
 	/**
-	 * Return the JDBC DataSource that this instance manages transactions for.
+	 * Return the JDBC {@code DataSource} that this instance manages transactions for.
 	 */
 	@Nullable
 	public DataSource getDataSource() {
@@ -182,7 +186,7 @@ public class DataSourceTransactionManager extends AbstractPlatformTransactionMan
 	}
 
 	/**
-	 * Obtain the DataSource for actual use.
+	 * Obtain the {@code DataSource} for actual use.
 	 * @return the DataSource (never {@code null})
 	 * @throws IllegalStateException in case of no DataSource set
 	 * @since 5.0

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/DataSourceUtils.java

@@ -33,9 +33,9 @@ import org.springframework.transaction.support.TransactionSynchronizationManager
 import org.springframework.util.Assert;
 
 /**
- * Helper class that provides static methods for obtaining JDBC Connections from
- * a {@link javax.sql.DataSource}. Includes special support for Spring-managed
- * transactional Connections, e.g. managed by {@link DataSourceTransactionManager}
+ * Helper class that provides static methods for obtaining JDBC {@code Connection}s
+ * from a {@link javax.sql.DataSource}. Includes special support for Spring-managed
+ * transactional {@code Connection}s, e.g. managed by {@link DataSourceTransactionManager}
  * or {@link org.springframework.transaction.jta.JtaTransactionManager}.
  *
  * <p>Used internally by Spring's {@link org.springframework.jdbc.core.JdbcTemplate},
@@ -46,7 +46,8 @@ import org.springframework.util.Assert;
  * @author Juergen Hoeller
  * @see #getConnection
  * @see #releaseConnection
- * @see DataSourceTransactionManager
+ * @see org.springframework.jdbc.core.JdbcTemplate
+ * @see org.springframework.jdbc.support.JdbcTransactionManager
  * @see org.springframework.transaction.jta.JtaTransactionManager
  * @see org.springframework.transaction.support.TransactionSynchronizationManager
  */
@@ -474,7 +475,7 @@ public abstract class DataSourceUtils {
 
 		private final DataSource dataSource;
 
-		private int order;
+		private final int order;
 
 		private boolean holderActive = true;
 

spring-jms/src/main/java/org/springframework/jms/config/DefaultJmsListenerContainerFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,8 +27,8 @@ import org.springframework.util.backoff.BackOff;
  * A {@link JmsListenerContainerFactory} implementation to build a regular
  * {@link DefaultMessageListenerContainer}.
  *
- * <p>This should be the default for most users and a good transition paths
- * for those that are used to build such container definition manually.
+ * <p>This should be the default for most users and a good transition path
+ * for those who are used to building such a container definition manually.
  *
  * @author Stephane Nicoll
  * @since 4.1
@@ -67,63 +67,63 @@ public class DefaultJmsListenerContainerFactory
 	/**
 	 * @see DefaultMessageListenerContainer#setTaskExecutor
 	 */
-	public void setTaskExecutor(Executor taskExecutor) {
+	public void setTaskExecutor(@Nullable Executor taskExecutor) {
 		this.taskExecutor = taskExecutor;
 	}
 
 	/**
 	 * @see DefaultMessageListenerContainer#setTransactionManager
 	 */
-	public void setTransactionManager(PlatformTransactionManager transactionManager) {
+	public void setTransactionManager(@Nullable PlatformTransactionManager transactionManager) {
 		this.transactionManager = transactionManager;
 	}
 
 	/**
 	 * @see DefaultMessageListenerContainer#setCacheLevel
 	 */
-	public void setCacheLevel(Integer cacheLevel) {
+	public void setCacheLevel(@Nullable Integer cacheLevel) {
 		this.cacheLevel = cacheLevel;
 	}
 
 	/**
 	 * @see DefaultMessageListenerContainer#setCacheLevelName
 	 */
-	public void setCacheLevelName(String cacheLevelName) {
+	public void setCacheLevelName(@Nullable String cacheLevelName) {
 		this.cacheLevelName = cacheLevelName;
 	}
 
 	/**
 	 * @see DefaultMessageListenerContainer#setConcurrency
 	 */
-	public void setConcurrency(String concurrency) {
+	public void setConcurrency(@Nullable String concurrency) {
 		this.concurrency = concurrency;
 	}
 
 	/**
 	 * @see DefaultMessageListenerContainer#setMaxMessagesPerTask
 	 */
-	public void setMaxMessagesPerTask(Integer maxMessagesPerTask) {
+	public void setMaxMessagesPerTask(@Nullable Integer maxMessagesPerTask) {
 		this.maxMessagesPerTask = maxMessagesPerTask;
 	}
 
 	/**
 	 * @see DefaultMessageListenerContainer#setReceiveTimeout
 	 */
-	public void setReceiveTimeout(Long receiveTimeout) {
+	public void setReceiveTimeout(@Nullable Long receiveTimeout) {
 		this.receiveTimeout = receiveTimeout;
 	}
 
 	/**
 	 * @see DefaultMessageListenerContainer#setRecoveryInterval
 	 */
-	public void setRecoveryInterval(Long recoveryInterval) {
+	public void setRecoveryInterval(@Nullable Long recoveryInterval) {
 		this.recoveryInterval = recoveryInterval;
 	}
 
 	/**
 	 * @see DefaultMessageListenerContainer#setBackOff
 	 */
-	public void setBackOff(BackOff backOff) {
+	public void setBackOff(@Nullable BackOff backOff) {
 		this.backOff = backOff;
 	}
 

spring-orm/src/main/java/org/springframework/orm/hibernate5/HibernateTransactionManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -105,7 +105,7 @@ import org.springframework.util.Assert;
  * @see DataSourceUtils#getConnection
  * @see DataSourceUtils#releaseConnection
  * @see org.springframework.jdbc.core.JdbcTemplate
- * @see org.springframework.jdbc.datasource.DataSourceTransactionManager
+ * @see org.springframework.jdbc.support.JdbcTransactionManager
  * @see org.springframework.transaction.jta.JtaTransactionManager
  */
 @SuppressWarnings("serial")

spring-orm/src/main/java/org/springframework/orm/jpa/JpaTransactionManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -109,7 +109,7 @@ import org.springframework.util.CollectionUtils;
  * @see org.springframework.jdbc.datasource.DataSourceUtils#getConnection
  * @see org.springframework.jdbc.datasource.DataSourceUtils#releaseConnection
  * @see org.springframework.jdbc.core.JdbcTemplate
- * @see org.springframework.jdbc.datasource.DataSourceTransactionManager
+ * @see org.springframework.jdbc.support.JdbcTransactionManager
  * @see org.springframework.transaction.jta.JtaTransactionManager
  */
 @SuppressWarnings("serial")

spring-orm/src/main/java/org/springframework/orm/jpa/SharedEntityManagerCreator.java

@@ -436,7 +436,7 @@ public abstract class SharedEntityManagerCreator {
 									entry.setValue(storedProc.getOutputParameterValue(key.toString()));
 								}
 							}
-							catch (IllegalArgumentException ex) {
+							catch (RuntimeException ex) {
 								entry.setValue(ex);
 							}
 						}

spring-orm/src/main/java/org/springframework/orm/jpa/vendor/EclipseLinkJpaDialect.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,6 +22,7 @@ import java.sql.SQLException;
 import javax.persistence.EntityManager;
 import javax.persistence.PersistenceException;
 
+import org.eclipse.persistence.sessions.DatabaseLogin;
 import org.eclipse.persistence.sessions.UnitOfWork;
 
 import org.springframework.jdbc.datasource.ConnectionHandle;
@@ -35,14 +36,20 @@ import org.springframework.transaction.TransactionException;
  * Persistence Services (EclipseLink). Developed and tested against EclipseLink 2.7;
  * backwards-compatible with EclipseLink 2.5 and 2.6 at runtime.
  *
- * <p>By default, this class acquires an early EclipseLink transaction with an early
- * JDBC Connection for non-read-only transactions. This allows for mixing JDBC and
- * JPA/EclipseLink operations in the same transaction, with cross visibility of
+ * <p>By default, this dialect acquires an early EclipseLink transaction with an
+ * early JDBC Connection for non-read-only transactions. This allows for mixing
+ * JDBC and JPA operations in the same transaction, with cross visibility of
  * their impact. If this is not needed, set the "lazyDatabaseTransaction" flag to
  * {@code true} or consistently declare all affected transactions as read-only.
  * As of Spring 4.1.2, this will reliably avoid early JDBC Connection retrieval
  * and therefore keep EclipseLink in shared cache mode.
  *
+ * <p><b>NOTE: This dialect supports custom isolation levels with limitations.</b>
+ * Consistent isolation level handling is only guaranteed when all Spring transaction
+ * definitions specify a concrete isolation level, without any default transactions
+ * running concurrently. Otherwise, you may see non-default isolation levels exposed
+ * to default transactions when custom isolation is used in concurrent transactions.
+ *
  * @author Juergen Hoeller
  * @since 2.5.2
  * @see #setLazyDatabaseTransaction
@@ -78,19 +85,38 @@ public class EclipseLinkJpaDialect extends DefaultJpaDialect {
 	public Object beginTransaction(EntityManager entityManager, TransactionDefinition definition)
 			throws PersistenceException, SQLException, TransactionException {
 
-		if (definition.getIsolationLevel() != TransactionDefinition.ISOLATION_DEFAULT) {
+		int currentIsolationLevel = definition.getIsolationLevel();
+		if (currentIsolationLevel != TransactionDefinition.ISOLATION_DEFAULT) {
 			// Pass custom isolation level on to EclipseLink's DatabaseLogin configuration
-			// (since Spring 4.1.2)
+			// (since Spring 4.1.2 / revised in 5.3.28)
 			UnitOfWork uow = entityManager.unwrap(UnitOfWork.class);
-			uow.getLogin().setTransactionIsolation(definition.getIsolationLevel());
+			DatabaseLogin databaseLogin = uow.getLogin();
+			// Synchronize on shared DatabaseLogin instance for consistent isolation level
+			// set and reset in case of concurrent transactions with different isolation.
+			synchronized (databaseLogin) {
+				int originalIsolationLevel = databaseLogin.getTransactionIsolation();
+				// Apply current isolation level value, if necessary.
+				if (currentIsolationLevel != originalIsolationLevel) {
+					databaseLogin.setTransactionIsolation(currentIsolationLevel);
+				}
+				// Transaction begin including enforced JDBC Connection access
+				// (picking up current isolation level from DatabaseLogin)
+				entityManager.getTransaction().begin();
+				uow.beginEarlyTransaction();
+				entityManager.unwrap(Connection.class);
+				// Restore original isolation level value, if necessary.
+				if (currentIsolationLevel != originalIsolationLevel) {
+					databaseLogin.setTransactionIsolation(originalIsolationLevel);
+				}
+			}
 		}
-
-		entityManager.getTransaction().begin();
-
-		if (!definition.isReadOnly() && !this.lazyDatabaseTransaction) {
-			// Begin an early transaction to force EclipseLink to get a JDBC Connection
-			// so that Spring can manage transactions with JDBC as well as EclipseLink.
-			entityManager.unwrap(UnitOfWork.class).beginEarlyTransaction();
+		else {
+			entityManager.getTransaction().begin();
+			if (!definition.isReadOnly() && !this.lazyDatabaseTransaction) {
+				// Begin an early transaction to force EclipseLink to get a JDBC Connection
+				// so that Spring can manage transactions with JDBC as well as EclipseLink.
+				entityManager.unwrap(UnitOfWork.class).beginEarlyTransaction();
+			}
 		}
 
 		return null;

spring-orm/src/test/java/org/springframework/orm/jpa/AbstractContainerEntityManagerFactoryIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,8 +27,10 @@ import javax.persistence.Query;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.core.testfixture.io.SerializationTestUtils;
+import org.springframework.jdbc.datasource.DataSourceUtils;
 import org.springframework.orm.jpa.domain.DriversLicense;
 import org.springframework.orm.jpa.domain.Person;
+import org.springframework.transaction.TransactionDefinition;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatException;
@@ -114,24 +116,34 @@ public abstract class AbstractContainerEntityManagerFactoryIntegrationTests
 	}
 
 	@Test
-	public void testLazyLoading() {
+	public void testLazyLoading() throws Exception {
 		try {
 			Person tony = new Person();
 			tony.setFirstName("Tony");
 			tony.setLastName("Blair");
 			tony.setDriversLicense(new DriversLicense("8439DK"));
 			sharedEntityManager.persist(tony);
+			assertThat(DataSourceUtils.getConnection(jdbcTemplate.getDataSource()).getTransactionIsolation())
+					.isEqualTo(TransactionDefinition.ISOLATION_READ_COMMITTED);
 			setComplete();
 			endTransaction();
 
+			transactionDefinition.setIsolationLevel(TransactionDefinition.ISOLATION_SERIALIZABLE);
 			startNewTransaction();
+			assertThat(DataSourceUtils.getConnection(jdbcTemplate.getDataSource()).getTransactionIsolation())
+					.isEqualTo(TransactionDefinition.ISOLATION_SERIALIZABLE);
 			sharedEntityManager.clear();
 			Person newTony = entityManagerFactory.createEntityManager().getReference(Person.class, tony.getId());
 			assertThat(tony).isNotSameAs(newTony);
 			endTransaction();
 
-			assertThat(newTony.getDriversLicense()).isNotNull();
+			transactionDefinition.setIsolationLevel(TransactionDefinition.ISOLATION_DEFAULT);
+			startNewTransaction();
+			assertThat(DataSourceUtils.getConnection(jdbcTemplate.getDataSource()).getTransactionIsolation())
+					.isEqualTo(TransactionDefinition.ISOLATION_READ_COMMITTED);
+			endTransaction();
 
+			assertThat(newTony.getDriversLicense()).isNotNull();
 			newTony.getDriversLicense().getSerialNumber();
 		}
 		finally {

spring-r2dbc/src/main/java/org/springframework/r2dbc/connection/R2dbcTransactionManager.java

@@ -36,41 +36,36 @@ import org.springframework.transaction.reactive.TransactionSynchronizationManage
 import org.springframework.util.Assert;
 
 /**
- * {@link org.springframework.transaction.ReactiveTransactionManager}
- * implementation for a single R2DBC {@link ConnectionFactory}. This class is
- * capable of working in any environment with any R2DBC driver, as long as the
- * setup uses a {@code ConnectionFactory} as its {@link Connection} factory
- * mechanism. Binds a R2DBC {@code Connection} from the specified
- * {@code ConnectionFactory} to the current subscriber context, potentially
- * allowing for one context-bound {@code Connection} per {@code ConnectionFactory}.
+ * {@link org.springframework.transaction.ReactiveTransactionManager} implementation
+ * for a single R2DBC {@link ConnectionFactory}. This class is capable of working
+ * in any environment with any R2DBC driver, as long as the setup uses a
+ * {@code ConnectionFactory} as its {@link Connection} factory mechanism.
+ * Binds a R2DBC {@code Connection} from the specified {@code ConnectionFactory}
+ * to the current subscriber context, potentially allowing for one context-bound
+ * {@code Connection} per {@code ConnectionFactory}.
  *
- * <p><b>Note: The {@code ConnectionFactory} that this transaction manager
- * operates on needs to return independent {@code Connection}s.</b>
- * The {@code Connection}s may come from a pool (the typical case), but the
- * {@code ConnectionFactory} must not return scoped {@code Connection}s
- * or the like. This transaction manager will associate {@code Connection}
- * with context-bound transactions itself, according to the specified propagation
- * behavior. It assumes that a separate, independent {@code Connection} can
- * be obtained even during an ongoing transaction.
+ * <p><b>Note: The {@code ConnectionFactory} that this transaction manager operates
+ * on needs to return independent {@code Connection}s.</b> The {@code Connection}s
+ * typically come from a connection pool but the {@code ConnectionFactory} must not
+ * return specifically scoped or constrained {@code Connection}s. This transaction
+ * manager will associate {@code Connection} with context-bound transactions,
+ * according to the specified propagation behavior. It assumes that a separate,
+ * independent {@code Connection} can be obtained even during an ongoing transaction.
  *
  * <p>Application code is required to retrieve the R2DBC Connection via
  * {@link ConnectionFactoryUtils#getConnection(ConnectionFactory)}
  * instead of a standard R2DBC-style {@link ConnectionFactory#create()} call.
  * Spring classes such as {@code DatabaseClient} use this strategy implicitly.
  * If not used in combination with this transaction manager, the
- * {@link ConnectionFactoryUtils} lookup strategy behaves exactly like the
- * native {@code ConnectionFactory} lookup; it can thus be used in a portable fashion.
+ * {@link ConnectionFactoryUtils} lookup strategy behaves exactly like the native
+ * {@code ConnectionFactory} lookup; it can thus be used in a portable fashion.
  *
- * <p>Alternatively, you can allow application code to work with the standard
- * R2DBC lookup pattern {@link ConnectionFactory#create()}, for example for code
- * that is not aware of Spring at all. In that case, define a
- * {@link TransactionAwareConnectionFactoryProxy} for your target {@code ConnectionFactory},
- * and pass that proxy {@code ConnectionFactory} to your DAOs, which will automatically
- * participate in Spring-managed transactions when accessing it.
- *
- * <p>This transaction manager triggers flush callbacks on registered transaction
- * synchronizations (if synchronization is generally active), assuming resources
- * operating on the underlying R2DBC {@code Connection}.
+ * <p>Alternatively, you can allow application code to work with the lookup pattern
+ * {@link ConnectionFactory#create()}, for example for code not aware of Spring.
+ * In that case, define a {@link TransactionAwareConnectionFactoryProxy} for your
+ * target {@code ConnectionFactory}, and pass that proxy {@code ConnectionFactory}
+ * to your DAOs which will automatically participate in Spring-managed transactions
+ * when accessing it.
  *
  * @author Mark Paluch
  * @since 5.3
@@ -89,7 +84,7 @@ public class R2dbcTransactionManager extends AbstractReactiveTransactionManager
 
 	/**
 	 * Create a new {@code R2dbcTransactionManager} instance.
-	 * A ConnectionFactory has to be set to be able to use it.
+	 * A {@code ConnectionFactory} has to be set to be able to use it.
 	 * @see #setConnectionFactory
 	 */
 	public R2dbcTransactionManager() {}
@@ -106,12 +101,13 @@ public class R2dbcTransactionManager extends AbstractReactiveTransactionManager
 
 
 	/**
-	 * Set the R2DBC {@link ConnectionFactory} that this instance should manage transactions for.
-	 * <p>This will typically be a locally defined {@code ConnectionFactory}, for example a connection pool.
-	 * <p><b>The {@code ConnectionFactory} passed in here needs to return independent {@link Connection}s.</b>
-	 * The {@code Connection}s may come from a pool (the typical case), but the {@code ConnectionFactory}
-	 * must not return scoped {@code Connection}s or the like.
-	 * @see TransactionAwareConnectionFactoryProxy
+	 * Set the R2DBC {@link ConnectionFactory} that this instance should manage transactions
+	 * for. This will typically be a locally defined {@code ConnectionFactory}, for example
+	 * an R2DBC connection pool.
+	 * <p><b>The {@code ConnectionFactory} passed in here needs to return independent
+	 * {@link Connection}s.</b> The {@code Connection}s typically come from a connection
+	 * pool but the {@code ConnectionFactory} must not return specifically scoped or
+	 * constrained {@code Connection}s.
 	 */
 	public void setConnectionFactory(@Nullable ConnectionFactory connectionFactory) {
 		this.connectionFactory = connectionFactory;
@@ -142,8 +138,8 @@ public class R2dbcTransactionManager extends AbstractReactiveTransactionManager
 	 * transactional connection: "SET TRANSACTION READ ONLY" as understood by Oracle,
 	 * MySQL and Postgres.
 	 * <p>The exact treatment, including any SQL statement executed on the connection,
-	 * can be customized through {@link #prepareTransactionalConnection(Connection, TransactionDefinition)}.
-	 * @see #prepareTransactionalConnection(Connection, TransactionDefinition)
+	 * can be customized through {@link #prepareTransactionalConnection}.
+	 * @see #prepareTransactionalConnection
 	 */
 	public void setEnforceReadOnly(boolean enforceReadOnly) {
 		this.enforceReadOnly = enforceReadOnly;

spring-test/src/main/java/org/springframework/test/web/client/match/MockRestRequestMatchers.java

@@ -125,11 +125,11 @@ public abstract class MockRestRequestMatchers {
 	 * @param name the name of the query parameter whose value(s) will be asserted
 	 * @param matcher the Hamcrest matcher to apply to the entire list of values
 	 * for the given query parameter
-	 * @since 5.3.26
+	 * @since 5.3.27
 	 * @see #queryParam(String, Matcher...)
 	 * @see #queryParam(String, String...)
 	 */
-	public static RequestMatcher queryParam(String name, Matcher<? super List<String>> matcher) {
+	public static RequestMatcher queryParamList(String name, Matcher<? super List<String>> matcher) {
 		return request -> {
 			MultiValueMap<String, String> params = getQueryParams(request);
 			List<String> paramValues = params.get(name);
@@ -147,14 +147,14 @@ public abstract class MockRestRequestMatchers {
 	 * values, effectively ignoring the additional parameter values. If the number
 	 * of provided {@code matchers} exceeds the number of query parameter values,
 	 * an {@link AssertionError} will be thrown to signal the mismatch.
-	 * <p>See {@link #queryParam(String, Matcher)} for a variant which accepts a
+	 * <p>See {@link #queryParamList(String, Matcher)} for a variant which accepts a
 	 * {@code Matcher} that applies to the entire list of values as opposed to
 	 * applying only to individual values.
 	 * @param name the name of the query parameter whose value(s) will be asserted
 	 * @param matchers the Hamcrest matchers to apply to individual query parameter
 	 * values; the n<sup>th</sup> matcher is applied to the n<sup>th</sup> query
 	 * parameter value
-	 * @see #queryParam(String, Matcher)
+	 * @see #queryParamList(String, Matcher)
 	 * @see #queryParam(String, String...)
 	 */
 	@SafeVarargs
@@ -175,14 +175,14 @@ public abstract class MockRestRequestMatchers {
 	 * parameter values, effectively ignoring the additional parameter values. If
 	 * the number of {@code expectedValues} exceeds the number of query parameter
 	 * values, an {@link AssertionError} will be thrown to signal the mismatch.
-	 * <p>See {@link #queryParam(String, Matcher)} for a variant which accepts a
+	 * <p>See {@link #queryParamList(String, Matcher)} for a variant which accepts a
 	 * Hamcrest {@code Matcher} that applies to the entire list of values as opposed
 	 * to asserting only individual values.
 	 * @param name the name of the query parameter whose value(s) will be asserted
 	 * @param expectedValues the expected values of individual query parameter values;
 	 * the n<sup>th</sup> expected value is compared to the n<sup>th</sup> query
 	 * parameter value
-	 * @see #queryParam(String, Matcher)
+	 * @see #queryParamList(String, Matcher)
 	 * @see #queryParam(String, Matcher...)
 	 */
 	public static RequestMatcher queryParam(String name, String... expectedValues) {
@@ -211,11 +211,11 @@ public abstract class MockRestRequestMatchers {
 	 * @param name the name of the header whose value(s) will be asserted
 	 * @param matcher the Hamcrest matcher to apply to the entire list of values
 	 * for the given header
-	 * @since 5.3.26
+	 * @since 5.3.27
 	 * @see #header(String, Matcher...)
 	 * @see #header(String, String...)
 	 */
-	public static RequestMatcher header(String name, Matcher<? super List<String>> matcher) {
+	public static RequestMatcher headerList(String name, Matcher<? super List<String>> matcher) {
 		return request -> {
 			List<String> headerValues = request.getHeaders().get(name);
 			if (headerValues == null) {
@@ -232,13 +232,13 @@ public abstract class MockRestRequestMatchers {
 	 * effectively ignoring the additional header values. If the number of
 	 * provided {@code matchers} exceeds the number of header values, an
 	 * {@link AssertionError} will be thrown to signal the mismatch.
-	 * <p>See {@link #header(String, Matcher)} for a variant which accepts a
+	 * <p>See {@link #headerList(String, Matcher)} for a variant which accepts a
 	 * Hamcrest {@code Matcher} that applies to the entire list of values as
 	 * opposed to applying only to individual values.
 	 * @param name the name of the header whose value(s) will be asserted
 	 * @param matchers the Hamcrest matchers to apply to individual header values;
 	 * the n<sup>th</sup> matcher is applied to the n<sup>th</sup> header value
-	 * @see #header(String, Matcher)
+	 * @see #headerList(String, Matcher)
 	 * @see #header(String, String...)
 	 */
 	@SafeVarargs
@@ -260,13 +260,13 @@ public abstract class MockRestRequestMatchers {
 	 * additional header values. If the number of {@code expectedValues} exceeds the
 	 * number of header values, an {@link AssertionError} will be thrown to signal the
 	 * mismatch.
-	 * <p>See {@link #header(String, Matcher)} for a variant which accepts a
+	 * <p>See {@link #headerList(String, Matcher)} for a variant which accepts a
 	 * Hamcrest {@code Matcher} that applies to the entire list of values as
 	 * opposed to applying only to individual values.
 	 * @param name the name of the header whose value(s) will be asserted
 	 * @param expectedValues the expected values of individual header values; the
 	 * n<sup>th</sup> expected value is compared to the n<sup>th</sup> header value
-	 * @see #header(String, Matcher)
+	 * @see #headerList(String, Matcher)
 	 * @see #header(String, Matcher...)
 	 */
 	public static RequestMatcher header(String name, String... expectedValues) {

spring-test/src/test/java/org/springframework/test/web/client/match/MockRestRequestMatchersTests.java

@@ -29,19 +29,17 @@ import org.springframework.mock.http.client.MockClientHttpRequest;
 
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.hamcrest.Matchers.allOf;
-import static org.hamcrest.Matchers.any;
 import static org.hamcrest.Matchers.anything;
 import static org.hamcrest.Matchers.contains;
 import static org.hamcrest.Matchers.containsInAnyOrder;
 import static org.hamcrest.Matchers.containsString;
-import static org.hamcrest.Matchers.either;
 import static org.hamcrest.Matchers.endsWith;
+import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.everyItem;
 import static org.hamcrest.Matchers.hasItem;
 import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.notNullValue;
-import static org.hamcrest.Matchers.nullValue;
 import static org.hamcrest.Matchers.startsWith;
 
 /**
@@ -164,7 +162,7 @@ class MockRestRequestMatchersTests {
 	@Test
 	void headerListMissing() {
 		assertThatAssertionError()
-			.isThrownBy(() -> MockRestRequestMatchers.header("foo", hasSize(2)).match(this.request))
+			.isThrownBy(() -> MockRestRequestMatchers.headerList("foo", hasSize(2)).match(this.request))
 			.withMessage("Expected header <foo> to exist but was null");
 	}
 
@@ -172,29 +170,18 @@ class MockRestRequestMatchersTests {
 	void headerListMatchers() throws IOException {
 		this.request.getHeaders().put("foo", Arrays.asList("bar", "baz"));
 
-		MockRestRequestMatchers.header("foo", containsInAnyOrder(endsWith("baz"), endsWith("bar"))).match(this.request);
-		MockRestRequestMatchers.header("foo", contains(is("bar"), is("baz"))).match(this.request);
-		MockRestRequestMatchers.header("foo", contains(is("bar"), anything())).match(this.request);
-		MockRestRequestMatchers.header("foo", hasItem(endsWith("baz"))).match(this.request);
-		MockRestRequestMatchers.header("foo", everyItem(startsWith("ba"))).match(this.request);
-		MockRestRequestMatchers.header("foo", hasSize(2)).match(this.request);
+		MockRestRequestMatchers.headerList("foo", containsInAnyOrder(endsWith("baz"), endsWith("bar"))).match(this.request);
+		MockRestRequestMatchers.headerList("foo", contains(is("bar"), is("baz"))).match(this.request);
+		MockRestRequestMatchers.headerList("foo", contains(is("bar"), anything())).match(this.request);
+		MockRestRequestMatchers.headerList("foo", hasItem(endsWith("baz"))).match(this.request);
+		MockRestRequestMatchers.headerList("foo", everyItem(startsWith("ba"))).match(this.request);
+		MockRestRequestMatchers.headerList("foo", hasSize(2)).match(this.request);
 
-		// These can be a bit ambiguous when reading the test (the compiler selects the list matcher):
-		MockRestRequestMatchers.header("foo", notNullValue()).match(this.request);
-		MockRestRequestMatchers.header("foo", is(anything())).match(this.request);
-		MockRestRequestMatchers.header("foo", allOf(notNullValue(), notNullValue())).match(this.request);
+		MockRestRequestMatchers.headerList("foo", notNullValue()).match(this.request);
+		MockRestRequestMatchers.headerList("foo", is(anything())).match(this.request);
+		MockRestRequestMatchers.headerList("foo", allOf(notNullValue(), notNullValue())).match(this.request);
 
-		// These are not as ambiguous thanks to an inner matcher that is either obviously list-oriented,
-		// string-oriented, or obviously a vararg of matchers
-
-		// list matcher version
-		MockRestRequestMatchers.header("foo", allOf(notNullValue(), hasSize(2))).match(this.request);
-
-		// vararg version
-		MockRestRequestMatchers.header("foo", allOf(notNullValue(), endsWith("ar"))).match(this.request);
-		MockRestRequestMatchers.header("foo", is((any(String.class)))).match(this.request);
-		MockRestRequestMatchers.header("foo", either(is("bar")).or(is(nullValue()))).match(this.request);
-		MockRestRequestMatchers.header("foo", is(notNullValue()), is(notNullValue())).match(this.request);
+		MockRestRequestMatchers.headerList("foo", allOf(notNullValue(), hasSize(2))).match(this.request);
 	}
 
 	@Test
@@ -202,27 +189,41 @@ class MockRestRequestMatchersTests {
 		this.request.getHeaders().put("foo", Arrays.asList("bar", "baz"));
 
 		assertThatAssertionError()
-			.isThrownBy(() -> MockRestRequestMatchers.header("foo", contains(containsString("ba"))).match(this.request))
+			.isThrownBy(() -> MockRestRequestMatchers.headerList("foo", contains(containsString("ba"))).match(this.request))
 			.withMessageContainingAll(
 					"Request header [foo] values",
 					"Expected: iterable containing [a string containing \"ba\"]",
 					"but: not matched: \"baz\"");
 
 		assertThatAssertionError()
-			.isThrownBy(() -> MockRestRequestMatchers.header("foo", hasItem(endsWith("ba"))).match(this.request))
+			.isThrownBy(() -> MockRestRequestMatchers.headerList("foo", hasItem(endsWith("ba"))).match(this.request))
 			.withMessageContainingAll(
 					"Request header [foo] values",
 					"Expected: a collection containing a string ending with \"ba\"",
 					"but: mismatches were: [was \"bar\", was \"baz\"]");
 
 		assertThatAssertionError()
-			.isThrownBy(() -> MockRestRequestMatchers.header("foo", everyItem(endsWith("ar"))).match(this.request))
+			.isThrownBy(() -> MockRestRequestMatchers.headerList("foo", everyItem(endsWith("ar"))).match(this.request))
 			.withMessageContainingAll(
 					"Request header [foo] values",
 					"Expected: every item is a string ending with \"ar\"",
 					"but: an item was \"baz\"");
 	}
 
+	@Test
+	void headerListDoesntHideHeaderWithSingleMatcher() throws IOException {
+		this.request.getHeaders().put("foo", Arrays.asList("bar", "baz"));
+
+		MockRestRequestMatchers.header("foo", equalTo("bar")).match(this.request);
+
+		assertThatAssertionError()
+				.isThrownBy(() -> MockRestRequestMatchers.headerList("foo", equalTo("bar")).match(this.request))
+				.withMessageContainingAll(
+						"Request header [foo] values",
+						"Expected: \"bar\"",
+						"but: was <[bar, baz]>");
+	}
+
 	@Test
 	void headers() throws Exception {
 		this.request.getHeaders().put("foo", Arrays.asList("bar", "baz"));
@@ -290,7 +291,7 @@ class MockRestRequestMatchersTests {
 	@Test
 	void queryParamListMissing() {
 		assertThatAssertionError()
-			.isThrownBy(() -> MockRestRequestMatchers.queryParam("foo", hasSize(2)).match(this.request))
+			.isThrownBy(() -> MockRestRequestMatchers.queryParamList("foo", hasSize(2)).match(this.request))
 			.withMessage("Expected query param <foo> to exist but was null");
 	}
 
@@ -298,29 +299,18 @@ class MockRestRequestMatchersTests {
 	void queryParamListMatchers() throws IOException {
 		this.request.setURI(URI.create("http://www.foo.example/a?foo=bar&foo=baz"));
 
-		MockRestRequestMatchers.queryParam("foo", containsInAnyOrder(endsWith("baz"), endsWith("bar"))).match(this.request);
-		MockRestRequestMatchers.queryParam("foo", contains(is("bar"), is("baz"))).match(this.request);
-		MockRestRequestMatchers.queryParam("foo", contains(is("bar"), anything())).match(this.request);
-		MockRestRequestMatchers.queryParam("foo", hasItem(endsWith("baz"))).match(this.request);
-		MockRestRequestMatchers.queryParam("foo", everyItem(startsWith("ba"))).match(this.request);
-		MockRestRequestMatchers.queryParam("foo", hasSize(2)).match(this.request);
+		MockRestRequestMatchers.queryParamList("foo", containsInAnyOrder(endsWith("baz"), endsWith("bar"))).match(this.request);
+		MockRestRequestMatchers.queryParamList("foo", contains(is("bar"), is("baz"))).match(this.request);
+		MockRestRequestMatchers.queryParamList("foo", contains(is("bar"), anything())).match(this.request);
+		MockRestRequestMatchers.queryParamList("foo", hasItem(endsWith("baz"))).match(this.request);
+		MockRestRequestMatchers.queryParamList("foo", everyItem(startsWith("ba"))).match(this.request);
+		MockRestRequestMatchers.queryParamList("foo", hasSize(2)).match(this.request);
 
-		// These can be a bit ambiguous when reading the test (the compiler selects the list matcher):
-		MockRestRequestMatchers.queryParam("foo", notNullValue()).match(this.request);
-		MockRestRequestMatchers.queryParam("foo", is(anything())).match(this.request);
-		MockRestRequestMatchers.queryParam("foo", allOf(notNullValue(), notNullValue())).match(this.request);
+		MockRestRequestMatchers.queryParamList("foo", notNullValue()).match(this.request);
+		MockRestRequestMatchers.queryParamList("foo", is(anything())).match(this.request);
+		MockRestRequestMatchers.queryParamList("foo", allOf(notNullValue(), notNullValue())).match(this.request);
 
-		// These are not as ambiguous thanks to an inner matcher that is either obviously list-oriented,
-		// string-oriented, or obviously a vararg of matchers
-
-		// list matcher version
-		MockRestRequestMatchers.queryParam("foo", allOf(notNullValue(), hasSize(2))).match(this.request);
-
-		// vararg version
-		MockRestRequestMatchers.queryParam("foo", allOf(notNullValue(), endsWith("ar"))).match(this.request);
-		MockRestRequestMatchers.queryParam("foo", is((any(String.class)))).match(this.request);
-		MockRestRequestMatchers.queryParam("foo", either(is("bar")).or(is(nullValue()))).match(this.request);
-		MockRestRequestMatchers.queryParam("foo", is(notNullValue()), is(notNullValue())).match(this.request);
+		MockRestRequestMatchers.queryParamList("foo", allOf(notNullValue(), hasSize(2))).match(this.request);
 	}
 
 	@Test
@@ -328,27 +318,41 @@ class MockRestRequestMatchersTests {
 		this.request.setURI(URI.create("http://www.foo.example/a?foo=bar&foo=baz"));
 
 		assertThatAssertionError()
-			.isThrownBy(() -> MockRestRequestMatchers.queryParam("foo", contains(containsString("ba"))).match(this.request))
+			.isThrownBy(() -> MockRestRequestMatchers.queryParamList("foo", contains(containsString("ba"))).match(this.request))
 			.withMessageContainingAll(
 				"Query param [foo] values",
 				"Expected: iterable containing [a string containing \"ba\"]",
 				"but: not matched: \"baz\"");
 
 		assertThatAssertionError()
-			.isThrownBy(() -> MockRestRequestMatchers.queryParam("foo", hasItem(endsWith("ba"))).match(this.request))
+			.isThrownBy(() -> MockRestRequestMatchers.queryParamList("foo", hasItem(endsWith("ba"))).match(this.request))
 			.withMessageContainingAll(
 				"Query param [foo] values",
 				"Expected: a collection containing a string ending with \"ba\"",
 				"but: mismatches were: [was \"bar\", was \"baz\"]");
 
 		assertThatAssertionError()
-			.isThrownBy(() -> MockRestRequestMatchers.queryParam("foo", everyItem(endsWith("ar"))).match(this.request))
+			.isThrownBy(() -> MockRestRequestMatchers.queryParamList("foo", everyItem(endsWith("ar"))).match(this.request))
 			.withMessageContainingAll(
 				"Query param [foo] values",
 				"Expected: every item is a string ending with \"ar\"",
 				"but: an item was \"baz\"");
 	}
 
+	@Test
+	void queryParamListDoesntHideQueryParamWithSingleMatcher() throws IOException {
+		this.request.setURI(URI.create("http://www.foo.example/a?foo=bar&foo=baz"));
+
+		MockRestRequestMatchers.queryParam("foo", equalTo("bar")).match(this.request);
+
+		assertThatAssertionError()
+				.isThrownBy(() -> MockRestRequestMatchers.queryParamList("foo", equalTo("bar")).match(this.request))
+				.withMessageContainingAll(
+						"Query param [foo] values",
+						"Expected: \"bar\"",
+						"but: was <[bar, baz]>");
+	}
+
 	private static ThrowableTypeAssert<AssertionError> assertThatAssertionError() {
 		return assertThatExceptionOfType(AssertionError.class);
 	}

spring-web/src/main/java/org/springframework/http/client/reactive/HttpComponentsClientHttpConnector.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -106,14 +106,12 @@ public class HttpComponentsClientHttpConnector implements ClientHttpConnector, C
 			Function<? super ClientHttpRequest, Mono<Void>> requestCallback) {
 
 		HttpClientContext context = this.contextProvider.apply(method, uri);
-
 		if (context.getCookieStore() == null) {
 			context.setCookieStore(new BasicCookieStore());
 		}
 
-		HttpComponentsClientHttpRequest request = new HttpComponentsClientHttpRequest(method, uri,
-				context, this.dataBufferFactory);
-
+		HttpComponentsClientHttpRequest request =
+				new HttpComponentsClientHttpRequest(method, uri, context, this.dataBufferFactory);
 		return requestCallback.apply(request).then(Mono.defer(() -> execute(request, context)));
 	}
 
@@ -123,7 +121,6 @@ public class HttpComponentsClientHttpConnector implements ClientHttpConnector, C
 		return Mono.create(sink -> {
 			ReactiveResponseConsumer reactiveResponseConsumer =
 					new ReactiveResponseConsumer(new MonoFutureCallbackAdapter(sink, this.dataBufferFactory, context));
-
 			this.client.execute(requestProducer, reactiveResponseConsumer, context, null);
 		});
 	}
@@ -133,6 +130,7 @@ public class HttpComponentsClientHttpConnector implements ClientHttpConnector, C
 		this.client.close();
 	}
 
+
 	private static class MonoFutureCallbackAdapter
 			implements FutureCallback<Message<HttpResponse, Publisher<ByteBuffer>>> {
 
@@ -144,6 +142,7 @@ public class HttpComponentsClientHttpConnector implements ClientHttpConnector, C
 
 		public MonoFutureCallbackAdapter(MonoSink<ClientHttpResponse> sink,
 				DataBufferFactory dataBufferFactory, HttpClientContext context) {
+
 			this.sink = sink;
 			this.dataBufferFactory = dataBufferFactory;
 			this.context = context;
@@ -151,19 +150,12 @@ public class HttpComponentsClientHttpConnector implements ClientHttpConnector, C
 
 		@Override
 		public void completed(Message<HttpResponse, Publisher<ByteBuffer>> result) {
-			HttpComponentsClientHttpResponse response =
-					new HttpComponentsClientHttpResponse(this.dataBufferFactory, result, this.context);
-			this.sink.success(response);
+			this.sink.success(new HttpComponentsClientHttpResponse(this.dataBufferFactory, result, this.context));
 		}
 
 		@Override
 		public void failed(Exception ex) {
-			Throwable t = ex;
-			if (t instanceof HttpStreamResetException) {
-				HttpStreamResetException httpStreamResetException = (HttpStreamResetException) ex;
-				t = httpStreamResetException.getCause();
-			}
-			this.sink.error(t);
+			this.sink.error(ex instanceof HttpStreamResetException && ex.getCause() != null ? ex.getCause() : ex);
 		}
 
 		@Override

spring-web/src/main/java/org/springframework/http/client/reactive/HttpComponentsHeadersAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -53,6 +53,7 @@ class HttpComponentsHeadersAdapter implements MultiValueMap<String, String> {
 
 
 	@Override
+	@Nullable
 	public String getFirst(String key) {
 		Header header = this.message.getFirstHeader(key);
 		return (header != null ? header.getValue() : null);

spring-web/src/main/java/org/springframework/http/server/reactive/ReactorServerHttpRequest.java

@@ -79,10 +79,12 @@ class ReactorServerHttpRequest extends AbstractServerHttpRequest {
 		return new URI(resolveBaseUrl(request) + resolveRequestUri(request));
 	}
 
-	private static String resolveBaseUrl(HttpServerRequest request) {
+	private static URI resolveBaseUrl(HttpServerRequest request) throws URISyntaxException {
 		String scheme = request.scheme();
 		int port = request.hostPort();
-		return scheme + "://" + request.hostName() + (usePort(scheme, port) ? ":" + port : "");
+		return (usePort(scheme, port) ?
+				new URI(scheme, null, request.hostName(), port, null, null, null) :
+				new URI(scheme, request.hostName(), null, null));
 	}
 
 	private static boolean usePort(String scheme, int port) {

spring-webflux/spring-webflux.gradle

@@ -1,6 +1,7 @@
 description = "Spring WebFlux"
 
 apply plugin: "kotlin"
+apply plugin: "kotlinx-serialization"
 
 dependencies {
 	api(project(":spring-beans"))
@@ -45,6 +46,7 @@ dependencies {
 	testImplementation('org.apache.httpcomponents.core5:httpcore5-reactive')
 	testImplementation("com.squareup.okhttp3:mockwebserver")
 	testImplementation("org.jetbrains.kotlin:kotlin-script-runtime")
+	testImplementation("org.jetbrains.kotlinx:kotlinx-serialization-json")
 	testRuntimeOnly("org.jetbrains.kotlin:kotlin-scripting-jsr223")
 	testRuntimeOnly("org.jruby:jruby")
 	testRuntimeOnly("org.python:jython-standalone")

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/AbstractMessageWriterResultHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -139,8 +139,15 @@ public abstract class AbstractMessageWriterResultHandler extends HandlerResultHa
 		}
 		else {
 			publisher = Mono.justOrEmpty(body);
-			actualElementType = body != null ? ResolvableType.forInstance(body) : bodyType;
-			elementType = (bodyType.toClass() == Object.class && body != null ? actualElementType : bodyType);
+			ResolvableType bodyInstanceType = ResolvableType.forInstance(body);
+			if (bodyType.toClass() == Object.class && body != null) {
+				actualElementType = bodyInstanceType;
+				elementType = bodyInstanceType;
+			}
+			else {
+				actualElementType = (body == null || bodyInstanceType.hasUnresolvableGenerics()) ? bodyType : bodyInstanceType;
+				elementType = bodyType;
+			}
 		}
 
 		if (elementType.resolve() == void.class || elementType.resolve() == Void.class) {

spring-webflux/src/test/java/org/springframework/web/reactive/config/DelegatingWebFluxConfigurationTests.java

@@ -112,7 +112,7 @@ public class DelegatingWebFluxConfigurationTests {
 		boolean condition = initializer.getValidator() instanceof LocalValidatorFactoryBean;
 		assertThat(condition).isTrue();
 		assertThat(initializer.getConversionService()).isSameAs(formatterRegistry.getValue());
-		assertThat(codecsConfigurer.getValue().getReaders().size()).isEqualTo(14);
+		assertThat(codecsConfigurer.getValue().getReaders()).hasSize(15);
 	}
 
 	@Test

spring-webflux/src/test/java/org/springframework/web/reactive/config/WebFluxConfigurationSupportTests.java

@@ -152,7 +152,7 @@ public class WebFluxConfigurationSupportTests {
 		assertThat(adapter).isNotNull();
 
 		List<HttpMessageReader<?>> readers = adapter.getMessageReaders();
-		assertThat(readers.size()).isEqualTo(14);
+		assertThat(readers).hasSize(15);
 
 		ResolvableType multiValueMapType = forClassWithGenerics(MultiValueMap.class, String.class, String.class);
 
@@ -207,7 +207,7 @@ public class WebFluxConfigurationSupportTests {
 		assertThat(handler.getOrder()).isEqualTo(0);
 
 		List<HttpMessageWriter<?>> writers = handler.getMessageWriters();
-		assertThat(writers.size()).isEqualTo(13);
+		assertThat(writers).hasSize(14);
 
 		assertHasMessageWriter(writers, forClass(byte[].class), APPLICATION_OCTET_STREAM);
 		assertHasMessageWriter(writers, forClass(ByteBuffer.class), APPLICATION_OCTET_STREAM);
@@ -235,7 +235,7 @@ public class WebFluxConfigurationSupportTests {
 		assertThat(handler.getOrder()).isEqualTo(100);
 
 		List<HttpMessageWriter<?>> writers = handler.getMessageWriters();
-		assertThat(writers.size()).isEqualTo(13);
+		assertThat(writers).hasSize(14);
 
 		assertHasMessageWriter(writers, forClass(byte[].class), APPLICATION_OCTET_STREAM);
 		assertHasMessageWriter(writers, forClass(ByteBuffer.class), APPLICATION_OCTET_STREAM);

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/MessageWriterResultHandlerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -62,6 +62,7 @@ import static org.springframework.web.testfixture.method.ResolvableMethod.on;
  * Unit tests for {@link AbstractMessageWriterResultHandler}.
  *
  * @author Rossen Stoyanchev
+ * @author Sebastien Deleuze
  */
 public class MessageWriterResultHandlerTests {
 
@@ -180,6 +181,17 @@ public class MessageWriterResultHandlerTests {
 		assertResponseBody("[{\"id\":123,\"name\":\"foo\"},{\"id\":456,\"name\":\"bar\"}]");
 	}
 
+	@Test
+	public void jacksonTypeWithSubTypeAndObjectReturnValue() {
+		MethodParameter returnType = on(TestController.class).resolveReturnType(Object.class);
+
+		SimpleBean body = new SimpleBean(123L, "foo");
+		this.resultHandler.writeBody(body, returnType, this.exchange).block(Duration.ofSeconds(5));
+
+		assertThat(this.exchange.getResponse().getHeaders().getContentType()).isEqualTo(APPLICATION_JSON);
+		assertResponseBody("{\"id\":123,\"name\":\"foo\"}");
+	}
+
 
 	private void assertResponseBody(String responseBody) {
 		StepVerifier.create(this.exchange.getResponse().getBody())
@@ -287,6 +299,8 @@ public class MessageWriterResultHandlerTests {
 		Identifiable identifiable() { return null; }
 
 		List<Identifiable> listIdentifiable() { return null; }
+
+		Object object() { return null; }
 	}
 
 }

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/RequestMappingIntegrationTests.java

@@ -47,6 +47,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Rossen Stoyanchev
  * @author Stephane Maldini
+ * @author Sebastien Deleuze
  * @since 5.0
  */
 class RequestMappingIntegrationTests extends AbstractRequestMappingIntegrationTests {
@@ -91,8 +92,8 @@ class RequestMappingIntegrationTests extends AbstractRequestMappingIntegrationTe
 	void stream(HttpServer httpServer) throws Exception {
 		startServer(httpServer);
 
-		String[] expected = {"0", "1", "2", "3", "4"};
-		assertThat(performGet("/stream", new HttpHeaders(), String[].class).getBody()).isEqualTo(expected);
+		Integer[] expected = {0, 1, 2, 3, 4};
+		assertThat(performGet("/stream", new HttpHeaders(), Integer[].class).getBody()).isEqualTo(expected);
 	}
 
 

spring-webflux/src/test/kotlin/org/springframework/web/reactive/result/method/annotation/KotlinMessageWriterResultHandlerTests.kt

@@ -0,0 +1,161 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.reactive.result.method.annotation
+
+import kotlinx.serialization.Serializable
+import org.assertj.core.api.Assertions
+import org.junit.jupiter.api.Test
+import org.springframework.core.ResolvableType
+import org.springframework.core.io.buffer.DataBuffer
+import org.springframework.http.MediaType
+import org.springframework.http.ResponseEntity
+import org.springframework.http.codec.EncoderHttpMessageWriter
+import org.springframework.http.codec.HttpMessageWriter
+import org.springframework.http.codec.json.Jackson2JsonEncoder
+import org.springframework.http.codec.json.KotlinSerializationJsonEncoder
+import org.springframework.util.ObjectUtils
+import org.springframework.web.bind.annotation.GetMapping
+import org.springframework.web.bind.annotation.RestController
+import org.springframework.web.reactive.accept.RequestedContentTypeResolverBuilder
+import org.springframework.web.testfixture.http.server.reactive.MockServerHttpRequest
+import org.springframework.web.testfixture.method.ResolvableMethod
+import org.springframework.web.testfixture.server.MockServerWebExchange
+import reactor.test.StepVerifier
+import java.nio.charset.StandardCharsets
+import java.time.Duration
+import java.util.*
+
+/**
+ * Kotlin unit tests for {@link AbstractMessageWriterResultHandler}.
+ *
+ * @author Sebastien Deleuze
+ */
+class KotlinMessageWriterResultHandlerTests {
+
+	private val resultHandler = initResultHandler()
+
+	private val exchange = MockServerWebExchange.from(MockServerHttpRequest.get("/path"))
+
+
+	private fun initResultHandler(vararg writers: HttpMessageWriter<*>): AbstractMessageWriterResultHandler {
+		val writerList = if (ObjectUtils.isEmpty(writers)) {
+			listOf(
+				EncoderHttpMessageWriter(KotlinSerializationJsonEncoder()),
+				EncoderHttpMessageWriter(Jackson2JsonEncoder())
+			)
+		} else {
+			listOf(*writers)
+		}
+		val resolver = RequestedContentTypeResolverBuilder().build()
+		return object : AbstractMessageWriterResultHandler(writerList, resolver) {}
+	}
+
+	@Test
+	fun nonSuspendWithoutResponseEntity() {
+		val returnType = ResolvableMethod.on(SampleController::class.java)
+			.resolveReturnType(List::class.java, Person::class.java)
+		val body = listOf(Person(UserId(1), "John"))
+		resultHandler.writeBody(body, returnType, exchange).block(Duration.ofSeconds(5))
+
+		Assertions.assertThat(exchange.response.headers.contentType).isEqualTo(MediaType.APPLICATION_JSON)
+		assertResponseBody("[{\"userId\":1,\"name\":\"John\"}]")
+	}
+
+	@Test
+	fun nonSuspendWithResponseEntity() {
+		val returnType = ResolvableMethod.on(SampleController::class.java)
+			.returning(ResolvableType.forClassWithGenerics(ResponseEntity::class.java,
+				ResolvableType.forClassWithGenerics(List::class.java, Person::class.java)))
+			.build().returnType()
+		val body = ResponseEntity.ok(listOf(Person(UserId(1), "John")))
+		resultHandler.writeBody(body.body, returnType.nested(), returnType, exchange).block(Duration.ofSeconds(5))
+
+		Assertions.assertThat(exchange.response.headers.contentType).isEqualTo(MediaType.APPLICATION_JSON)
+		assertResponseBody("[{\"userId\":1,\"name\":\"John\"}]")
+	}
+
+	@Test
+	fun suspendWithoutResponseEntity() {
+		val returnType = ResolvableMethod.on(CoroutinesSampleController::class.java)
+			.resolveReturnType(List::class.java, Person::class.java)
+		val body = listOf(Person(UserId(1), "John"))
+		resultHandler.writeBody(body, returnType, exchange).block(Duration.ofSeconds(5))
+
+		Assertions.assertThat(exchange.response.headers.contentType).isEqualTo(MediaType.APPLICATION_JSON)
+		assertResponseBody("[{\"userId\":1,\"name\":\"John\"}]")
+	}
+
+	@Test
+	fun suspendWithResponseEntity() {
+		val returnType = ResolvableMethod.on(CoroutinesSampleController::class.java)
+			.returning(ResolvableType.forClassWithGenerics(ResponseEntity::class.java,
+				ResolvableType.forClassWithGenerics(List::class.java, Person::class.java)))
+			.build().returnType()
+		val body = ResponseEntity.ok(listOf(Person(UserId(1), "John")))
+		resultHandler.writeBody(body.body, returnType.nested(), returnType, exchange).block(Duration.ofSeconds(5))
+
+		Assertions.assertThat(exchange.response.headers.contentType).isEqualTo(MediaType.APPLICATION_JSON)
+		assertResponseBody("[{\"userId\":1,\"name\":\"John\"}]")
+	}
+
+	private fun assertResponseBody(responseBody: String) {
+		StepVerifier.create(exchange.response.body)
+			.consumeNextWith { buf: DataBuffer ->
+				Assertions.assertThat(
+					buf.toString(StandardCharsets.UTF_8)
+				).isEqualTo(responseBody)
+			}
+			.expectComplete()
+			.verify()
+	}
+
+	@RestController
+	class SampleController {
+
+		@GetMapping("/non-suspend-with-response-entity")
+		fun withResponseEntity(): ResponseEntity<List<Person>> =
+			TODO()
+
+		@GetMapping("/non-suspend-without-response-entity")
+		fun withoutResponseEntity(): List<Person> =
+			TODO()
+	}
+
+	@RestController
+	class CoroutinesSampleController {
+
+		@GetMapping("/suspend-with-response-entity")
+		suspend fun suspendAndResponseEntity(): ResponseEntity<List<Person>> =
+			TODO()
+
+		@GetMapping("/suspend-without-response-entity")
+		suspend fun suspendWithoutResponseEntity(): List<Person> =
+			TODO()
+
+	}
+
+	@Serializable
+	data class Person(
+		val userId: UserId,
+		val name: String,
+	)
+
+	@JvmInline
+	@Serializable
+	value class UserId(val id: Int)
+
+}

spring-webmvc/src/main/java/org/springframework/web/servlet/function/SseServerResponse.java

@@ -48,6 +48,7 @@ import org.springframework.web.servlet.ModelAndView;
  * <a href="https://www.w3.org/TR/eventsource/">Server-Sent Events</a>.
  *
  * @author Arjen Poutsma
+ * @author Sebastien Deleuze
  * @since 5.3.2
  */
 final class SseServerResponse extends AbstractServerResponse {
@@ -90,7 +91,7 @@ final class SseServerResponse extends AbstractServerResponse {
 		}
 
 		DefaultAsyncServerResponse.writeAsync(request, response, result);
-		this.sseConsumer.accept(new DefaultSseBuilder(response, context, result));
+		this.sseConsumer.accept(new DefaultSseBuilder(response, context, result, this.headers()));
 		return null;
 	}
 
@@ -113,15 +114,19 @@ final class SseServerResponse extends AbstractServerResponse {
 
 		private final List<HttpMessageConverter<?>> messageConverters;
 
+		private final HttpHeaders httpHeaders;
+
 		private final StringBuilder builder = new StringBuilder();
 
 		private boolean sendFailed;
 
 
-		public DefaultSseBuilder(HttpServletResponse response, Context context, DeferredResult<?> deferredResult) {
+		public DefaultSseBuilder(HttpServletResponse response, Context context, DeferredResult<?> deferredResult,
+				HttpHeaders httpHeaders) {
 			this.outputMessage = new ServletServerHttpResponse(response);
 			this.deferredResult = deferredResult;
 			this.messageConverters = context.messageConverters();
+			this.httpHeaders = httpHeaders;
 		}
 
 		@Override
@@ -206,7 +211,7 @@ final class SseServerResponse extends AbstractServerResponse {
 				for (HttpMessageConverter<?> converter : this.messageConverters) {
 					if (converter.canWrite(dataClass, MediaType.APPLICATION_JSON)) {
 						HttpMessageConverter<Object> objectConverter = (HttpMessageConverter<Object>) converter;
-						ServerHttpResponse response = new MutableHeadersServerHttpResponse(this.outputMessage);
+						ServerHttpResponse response = new MutableHeadersServerHttpResponse(this.outputMessage, this.httpHeaders);
 						objectConverter.write(data, MediaType.APPLICATION_JSON, response);
 						this.outputMessage.getBody().write(NL_NL);
 						this.outputMessage.flush();
@@ -276,9 +281,10 @@ final class SseServerResponse extends AbstractServerResponse {
 
 			private final HttpHeaders mutableHeaders = new HttpHeaders();
 
-			public MutableHeadersServerHttpResponse(ServerHttpResponse delegate) {
+			public MutableHeadersServerHttpResponse(ServerHttpResponse delegate, HttpHeaders headers) {
 				super(delegate);
 				this.mutableHeaders.putAll(delegate.getHeaders());
+				this.mutableHeaders.putAll(headers);
 			}
 
 			@Override

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilder.java

@@ -776,9 +776,27 @@ public class MvcUriComponentsBuilder {
 			}
 
 			else if (controllerType.isInterface()) {
-				return (T) Proxy.newProxyInstance(controllerType.getClassLoader(),
-						new Class<?>[] {controllerType, MethodInvocationInfo.class},
-						interceptor);
+				ClassLoader classLoader = controllerType.getClassLoader();
+				if (classLoader == null) {
+					// JDK bootstrap loader -> use MethodInvocationInfo ClassLoader instead.
+					classLoader = MethodInvocationInfo.class.getClassLoader();
+				}
+				else if (classLoader.getParent() == null) {
+					// Potentially the JDK platform loader on JDK 9+
+					ClassLoader miiClassLoader = MethodInvocationInfo.class.getClassLoader();
+					ClassLoader miiParent = miiClassLoader.getParent();
+					while (miiParent != null) {
+						if (classLoader == miiParent) {
+							// Suggested ClassLoader is ancestor of MethodInvocationInfo ClassLoader
+							// -> use MethodInvocationInfo ClassLoader itself instead.
+							classLoader = miiClassLoader;
+							break;
+						}
+						miiParent = miiParent.getParent();
+					}
+				}
+				Class<?>[] ifcs = new Class<?>[] {controllerType, MethodInvocationInfo.class};
+				return (T) Proxy.newProxyInstance(classLoader, ifcs, interceptor);
 			}
 
 			else {

spring-webmvc/src/test/java/org/springframework/web/servlet/function/SseServerResponseTests.java

@@ -33,6 +33,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * @author Arjen Poutsma
+ * @author Sebastien Deleuze
  */
 class SseServerResponseTests {
 
@@ -89,6 +90,33 @@ class SseServerResponseTests {
 		assertThat(this.mockResponse.getContentAsString()).isEqualTo(expected);
 	}
 
+	@Test
+	void sendObjectWithPrettyPrint() throws Exception {
+		Person person = new Person("John Doe", 42);
+		ServerResponse response = ServerResponse.sse(sse -> {
+			try {
+				sse.send(person);
+			}
+			catch (IOException ex) {
+				throw new UncheckedIOException(ex);
+			}
+		});
+
+		MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
+		converter.setPrettyPrint(true);
+		ServerResponse.Context context = () -> Collections.singletonList(converter);
+
+		ModelAndView mav = response.writeTo(this.mockRequest, this.mockResponse, context);
+		assertThat(mav).isNull();
+
+		String expected = "data:{\n" +
+				"data:  \"name\" : \"John Doe\",\n" +
+				"data:  \"age\" : 42\n" +
+				"data:}\n" +
+				"\n";
+		assertThat(this.mockResponse.getContentAsString()).isEqualTo(expected);
+	}
+
 	@Test
 	void builder() throws Exception {
 		ServerResponse response = ServerResponse.sse(sse -> {