Release v5.3.27

This commit introduces infrastructure to differentiate between
programmatic setting of a variable in an EvaluationContext versus the
assignment of a variable within a SpEL expression using the assignment
operator (=). In addition, this commit disables variable assignment
within expressions when using the SimpleEvaluationContext.

Closes gh-30327

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:4.1.91.Final"
+			mavenBom "io.projectreactor:reactor-bom:2020.0.31"
 			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"
@@ -340,7 +340,7 @@ configure([rootProject] + javaProjects) { project ->
 	}
 
 	checkstyle {
-		toolVersion = "10.9.1"
+		toolVersion = "10.9.3"
 		configDirectory.set(rootProject.file("src/checkstyle"))
 	}
 

gradle.properties

@@ -1,4 +1,4 @@
-version=5.3.26-SNAPSHOT
+version=5.3.27
 org.gradle.jvmargs=-Xmx2048m
 org.gradle.caching=true
 org.gradle.parallel=true

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.
@@ -123,6 +123,11 @@ final class JdkDynamicAopProxy implements AopProxy, InvocationHandler, Serializa
 		if (logger.isTraceEnabled()) {
 			logger.trace("Creating JDK dynamic proxy: " + this.advised.getTargetSource());
 		}
+		if (classLoader == null || classLoader.getParent() == null) {
+			// JDK bootstrap loader or platform loader suggested ->
+			// use higher-level loader which can see Spring infrastructure classes
+			classLoader = getClass().getClassLoader();
+		}
 		return Proxy.newProxyInstance(classLoader, this.proxiedInterfaces, this);
 	}
 

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 +383,40 @@ 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();
+		assertThat(((CharSequence) pf.getProxy(cl)).toString()).isEqualTo(target);
+	}
+
+	@Test
+	public void testDateProxy() {
+		Date target = new Date();
+		ProxyFactory pf = new ProxyFactory(target);
+		pf.setProxyTargetClass(true);
+		ClassLoader cl = target.getClass().getClassLoader();
+		assertThat(((Date) pf.getProxy(cl)).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();
+		assertThat(((Savepoint) pf.getProxy(cl)).getSavepointName()).isEqualTo("sp");
+	}
+
 
 	@Order(2)
 	public static class A implements Runnable {
@@ -391,7 +428,7 @@ public class ProxyFactoryTests {
 
 
 	@Order(1)
-	public static class B implements Runnable{
+	public static class B implements Runnable {
 
 		@Override
 		public void run() {

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/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-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/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/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.
@@ -17,8 +17,13 @@
 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;
@@ -653,6 +658,7 @@ 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 +914,73 @@ 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 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 type</em> is any of the following:
+	 * a primitive wrapper (excluding {@link Void}), an {@link Enum}, a {@link Number},
+	 * a {@link Date}, a {@link Temporal}, a {@link URI}, a {@link URL}, or a {@link 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);
+	}
+
+	/**
+	 * Copy of {@link org.springframework.beans.BeanUtils#isSimpleValueType(Class)}.
+	 * <p>Check if the given type represents a "simple" value type: a primitive or
+	 * primitive wrapper, an enum, a String or other CharSequence, a Number, a
+	 * Date, a Temporal, a URI, a URL, a Locale, or a Class.
+	 * <p>{@code Void} and {@code void} are not considered simple value types.
+	 * @param type the type to check
+	 * @return whether the given type represents a "simple" value type
+	 */
+	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) ||
+				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/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 +17,25 @@
 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 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;
 
@@ -816,7 +826,144 @@ class ObjectUtilsTests {
 			.withMessage("Constant [bogus] does not exist in enum type org.springframework.util.ObjectUtilsTests$Tropes");
 	}
 
-	private void assertEqualHashCodes(int expected, Object array) {
+	@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 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() + "@";
+		}
+
+	}
+
+
+	private static void assertEqualHashCodes(int expected, Object array) {
 		int actual = ObjectUtils.nullSafeHashCode(array);
 		assertThat(actual).isEqualTo(expected);
 		assertThat(array.hashCode() != actual).isTrue();

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/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/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;
@@ -92,6 +93,12 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 
 	private static final Pattern VALID_QUALIFIED_ID_PATTERN = Pattern.compile("[\\p{L}\\p{N}_$]+");
 
+	/**
+	 * Maximum length permitted for a SpEL expression.
+	 * @since 5.2.24
+	 */
+	private static final int MAX_EXPRESSION_LENGTH = 10_000;
+
 
 	private final SpelParserConfiguration configuration;
 
@@ -127,6 +134,8 @@ 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 +157,12 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 		}
 	}
 
+	private void checkExpressionLength(String string) {
+		if (string.length() > MAX_EXPRESSION_LENGTH) {
+			throw new SpelEvaluationException(SpelMessage.MAX_EXPRESSION_LENGTH_EXCEEDED, MAX_EXPRESSION_LENGTH);
+		}
+	}
+
 	//	expression
 	//    : logicalOrExpression
 	//      ( (ASSIGN^ logicalOrExpression)

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/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 +63,20 @@ 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 createListsOnAttemptToIndexNull01() throws EvaluationException, ParseException {
 			ExpressionParser parser = new SpelExpressionParser(new SpelParserConfiguration(true, true));
@@ -135,8 +152,24 @@ 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 +515,13 @@ 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 +1499,15 @@ 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-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-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 +776,14 @@ 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 || classLoader.getParent() == null) {
+					// JDK interface type from bootstrap loader or platform loader ->
+					// use higher-level loader which can see Spring infrastructure classes
+					classLoader = MethodInvocationInfo.class.getClassLoader();
+				}
+				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 -> {

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2023 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.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
+import java.sql.Savepoint;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Optional;
@@ -378,7 +379,7 @@ public class MvcUriComponentsBuilderTests {
 		assertThat(uriComponents.encode().toUri().toString()).isEqualTo("http://localhost/hotels/42/bookings/21");
 	}
 
-	@Test // SPR-16710
+	@Test  // SPR-16710
 	public void fromMethodCallWithStringReturnType() {
 		assertThatIllegalStateException().isThrownBy(() -> {
 				UriComponents uriComponents = fromMethodCall(
@@ -395,9 +396,24 @@ public class MvcUriComponentsBuilderTests {
 		assertThat(uriComponents.encode().toUri().toString()).isEqualTo("http://localhost/hotels/42/bookings/21");
 	}
 
+	@Test  // gh-30210
+	public void fromMethodCallWithCharSequenceReturnType() {
+		UriComponents uriComponents = fromMethodCall(
+				on(BookingControllerWithCharSequence.class).getBooking(21L)).buildAndExpand(42);
+
+		assertThat(uriComponents.encode().toUri().toString()).isEqualTo("http://localhost/hotels/42/bookings/21");
+	}
+
+	@Test  // gh-30210
+	public void fromMethodCallWithJdbc30115ReturnType() {
+		UriComponents uriComponents = fromMethodCall(
+				on(BookingControllerWithJdbcSavepoint.class).getBooking(21L)).buildAndExpand(42);
+
+		assertThat(uriComponents.encode().toUri().toString()).isEqualTo("http://localhost/hotels/42/bookings/21");
+	}
+
 	@Test
 	public void fromMappingNamePlain() {
-
 		initWebApplicationContext(WebConfig.class);
 
 		this.request.setServerName("example.org");
@@ -411,7 +427,6 @@ public class MvcUriComponentsBuilderTests {
 
 	@Test
 	public void fromMappingNameWithCustomBaseUrl() {
-
 		initWebApplicationContext(WebConfig.class);
 
 		UriComponentsBuilder baseUrl = UriComponentsBuilder.fromUriString("https://example.org:9999/base");
@@ -420,9 +435,8 @@ public class MvcUriComponentsBuilderTests {
 		assertThat(url).isEqualTo("https://example.org:9999/base/people/123/addresses/DE");
 	}
 
-	@Test // SPR-17027
+	@Test  // SPR-17027
 	public void fromMappingNameWithEncoding() {
-
 		initWebApplicationContext(WebConfig.class);
 
 		this.request.setServerName("example.org");
@@ -436,7 +450,6 @@ public class MvcUriComponentsBuilderTests {
 
 	@Test
 	public void fromMappingNameWithPathWithoutLeadingSlash() {
-
 		initWebApplicationContext(PathWithoutLeadingSlashConfig.class);
 
 		this.request.setServerName("example.org");
@@ -450,7 +463,6 @@ public class MvcUriComponentsBuilderTests {
 
 	@Test
 	public void fromControllerWithPrefix() {
-
 		initWebApplicationContext(PathPrefixWebConfig.class);
 
 		this.request.setScheme("https");
@@ -463,7 +475,6 @@ public class MvcUriComponentsBuilderTests {
 
 	@Test
 	public void fromMethodWithPrefix() {
-
 		initWebApplicationContext(PathPrefixWebConfig.class);
 
 		this.request.setScheme("https");
@@ -701,4 +712,26 @@ public class MvcUriComponentsBuilderTests {
 		}
 	}
 
+
+	@Controller
+	@RequestMapping("/hotels/{hotel}")
+	static class BookingControllerWithCharSequence {
+
+		@GetMapping("/bookings/{booking}")
+		public CharSequence getBooking(@PathVariable Long booking) {
+			return "url";
+		}
+	}
+
+
+	@Controller
+	@RequestMapping("/hotels/{hotel}")
+	static class BookingControllerWithJdbcSavepoint {
+
+		@GetMapping("/bookings/{booking}")
+		public Savepoint getBooking(@PathVariable Long booking) {
+			return null;
+		}
+	}
+
 }

spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/EnableWebSocket.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.
@@ -49,7 +49,7 @@ import org.springframework.context.annotation.Import;
  *         registry.addHandler(echoWebSocketHandler(), "/echo").withSockJS();
  * 	   }
  *
- *	   @Override
+ *	   @Bean
  *	   public WebSocketHandler echoWebSocketHandler() {
  *         return new EchoWebSocketHandler();
  *     }

src/docs/asciidoc/index.adoc

@@ -12,7 +12,7 @@ Spring MVC Test, WebTestClient.
 JDBC, R2DBC, O/R Mapping, XML Marshalling.
 <<web.adoc#spring-web, Web Servlet>> :: Spring MVC, WebSocket, SockJS,
 STOMP Messaging.
-<<web-reactive.adoc#spring-webflux, Web Reactive>> :: Spring WebFlux, WebClient,
+<<web-reactive.adoc#spring-web-reactive, Web Reactive>> :: Spring WebFlux, WebClient,
 WebSocket, RSocket.
 <<integration.adoc#spring-integration, Integration>> :: Remoting, JMS, JCA, JMX,
 Email, Tasks, Scheduling, Caching.

src/docs/asciidoc/web/webflux.adoc

@@ -1625,7 +1625,7 @@ content types that a controller method produces, as the following example shows:
 ----
 	@GetMapping("/pets/{petId}", produces = ["application/json"])
 	@ResponseBody
-	fun getPet(@PathVariable String petId): Pet {
+	fun getPet(@PathVariable petId: String): Pet {
 		// ...
 	}
 ----
@@ -1674,7 +1674,7 @@ You can also use the same with request header conditions, as the following examp
 [source,java,indent=0,subs="verbatim,quotes",role="primary"]
 .Java
 ----
-	@GetMapping(path = "/pets", headers = "myHeader=myValue") // <1>
+	@GetMapping(path = "/pets/{petId}", headers = "myHeader=myValue") // <1>
 	public void findPet(@PathVariable String petId) {
 		// ...
 	}
@@ -1684,7 +1684,7 @@ You can also use the same with request header conditions, as the following examp
 [source,kotlin,indent=0,subs="verbatim,quotes",role="secondary"]
 .Kotlin
 ----
-	@GetMapping("/pets", headers = ["myHeader=myValue"]) // <1>
+	@GetMapping("/pets/{petId}", headers = ["myHeader=myValue"]) // <1>
 	fun findPet(@PathVariable petId: String) {
 		// ...
 	}

src/docs/asciidoc/web/webmvc.adoc

@@ -1911,7 +1911,7 @@ You can also use the same with request header conditions, as the following examp
 [source,java,indent=0,subs="verbatim,quotes",role="primary"]
 .Java
 ----
-	@GetMapping(path = "/pets", headers = "myHeader=myValue") // <1>
+	@GetMapping(path = "/pets/{petId}", headers = "myHeader=myValue") // <1>
 	public void findPet(@PathVariable String petId) {
 		// ...
 	}
@@ -1921,7 +1921,7 @@ You can also use the same with request header conditions, as the following examp
 [source,kotlin,indent=0,subs="verbatim,quotes",role="secondary"]
 .Kotlin
 ----
-	@GetMapping("/pets", headers = ["myHeader=myValue"]) // <1>
+	@GetMapping("/pets/{petId}", headers = ["myHeader=myValue"]) // <1>
 	fun findPet(@PathVariable petId: String) {
 		// ...
 	}