Switch to JSpecify annotations

This commit updates the whole Spring Framework codebase to use JSpecify
annotations instead of Spring null-safety annotations with JSR 305
semantics.

JSpecify provides signficant enhancements such as properly defined
specifications, a canonical dependency with no split-package issue,
better tooling, better Kotlin integration and the capability to specify
generic type, array and varargs element null-safety. Generic type
null-safety is not defined by this commit yet and will be specified
later.

A key difference is that Spring null-safety annotations, following
JSR 305 semantics, apply to fields, parameters and return values,
while JSpecify annotations apply to type usages. That's why this
commit moves nullability annotations closer to the type for fields
and return values.

See gh-28797

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

@@ -29,6 +29,7 @@ import jakarta.servlet.ServletRequest;
 import jakarta.servlet.ServletResponse;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.BeansException;
 import org.springframework.beans.MutablePropertyValues;
@@ -39,7 +40,6 @@ import org.springframework.context.i18n.LocaleContextHolder;
 import org.springframework.context.support.ApplicationObjectSupport;
 import org.springframework.core.Ordered;
 import org.springframework.http.HttpHeaders;
-import org.springframework.lang.Nullable;
 import org.springframework.ui.ModelMap;
 import org.springframework.web.bind.ServletRequestBindingException;
 import org.springframework.web.context.WebApplicationContext;

spring-webmvc/src/test/java/org/springframework/web/servlet/config/AnnotationDrivenBeanDefinitionParserTests.java

@@ -18,6 +18,7 @@ package org.springframework.web.servlet.config;
 
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.DirectFieldAccessor;
@@ -28,7 +29,6 @@ import org.springframework.core.io.Resource;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.ResourceHttpMessageConverter;
 import org.springframework.http.converter.StringHttpMessageConverter;
-import org.springframework.lang.Nullable;
 import org.springframework.util.AntPathMatcher;
 import org.springframework.validation.MessageCodesResolver;
 import org.springframework.web.bind.support.ConfigurableWebBindingInitializer;

spring-webmvc/src/test/java/org/springframework/web/servlet/config/MvcNamespaceTests.java

@@ -39,6 +39,7 @@ import com.fasterxml.jackson.dataformat.xml.XmlMapper;
 import jakarta.servlet.RequestDispatcher;
 import jakarta.servlet.http.MappingMatch;
 import jakarta.validation.constraints.NotNull;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -61,7 +62,6 @@ import org.springframework.http.MediaType;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter;
 import org.springframework.http.converter.xml.MappingJackson2XmlHttpMessageConverter;
-import org.springframework.lang.Nullable;
 import org.springframework.scheduling.concurrent.ConcurrentTaskExecutor;
 import org.springframework.stereotype.Controller;
 import org.springframework.util.AntPathMatcher;

spring-webmvc/src/test/java/org/springframework/web/servlet/config/annotation/InterceptorRegistryTests.java

@@ -21,11 +21,11 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.core.Ordered;
-import org.springframework.lang.Nullable;
 import org.springframework.ui.ModelMap;
 import org.springframework.util.AntPathMatcher;
 import org.springframework.util.PathMatcher;

spring-webmvc/src/test/java/org/springframework/web/servlet/config/annotation/WebMvcConfigurationSupportExtensionTests.java

@@ -23,6 +23,7 @@ import java.util.List;
 import java.util.Map;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -35,7 +36,6 @@ import org.springframework.http.HttpStatus;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
-import org.springframework.lang.Nullable;
 import org.springframework.scheduling.concurrent.ConcurrentTaskExecutor;
 import org.springframework.stereotype.Controller;
 import org.springframework.util.AntPathMatcher;

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

@@ -25,8 +25,9 @@ import java.util.Optional;
 import java.util.function.Function;
 import java.util.stream.Stream;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.io.Resource;
-import org.springframework.lang.Nullable;
 
 /**
  * @author Arjen Poutsma
@@ -37,8 +38,7 @@ class AttributesTestVisitor implements RouterFunctions.Visitor {
 
 	private final List<List<Map<String, Object>>> routerFunctionsAttributes = new LinkedList<>();
 
-	@Nullable
-	private Map<String, Object> attributes;
+	private @Nullable Map<String, Object> attributes;
 
 	private int visitCount;
 

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

@@ -21,12 +21,12 @@ import java.util.List;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.MediaType;
-import org.springframework.lang.Nullable;
 import org.springframework.web.servlet.handler.PathPatternsTestUtils;
 import org.springframework.web.testfixture.servlet.MockHttpServletRequest;
 import org.springframework.web.util.pattern.PathPatternParser;

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

@@ -24,6 +24,7 @@ import java.util.Optional;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Consumer;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.core.io.ClassPathResource;
@@ -32,7 +33,6 @@ import org.springframework.http.CacheControl;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.HttpStatusCode;
 import org.springframework.http.MediaType;
-import org.springframework.lang.Nullable;
 import org.springframework.web.servlet.handler.PathPatternsTestUtils;
 import org.springframework.web.testfixture.servlet.MockHttpServletRequest;
 

spring-webmvc/src/test/java/org/springframework/web/servlet/handler/AbstractUrlHandlerMappingTests.java

@@ -19,10 +19,10 @@ package org.springframework.web.servlet.handler;
 import java.util.Map;
 import java.util.function.Consumer;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.context.support.StaticApplicationContext;
-import org.springframework.lang.Nullable;
 
 import static java.util.Map.entry;
 import static org.assertj.core.api.Assertions.assertThat;

spring-webmvc/src/test/java/org/springframework/web/servlet/handler/CorsAbstractHandlerMappingTests.java

@@ -21,13 +21,13 @@ import java.util.stream.Stream;
 
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Named;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.server.RequestPath;
-import org.springframework.lang.Nullable;
 import org.springframework.web.HttpRequestHandler;
 import org.springframework.web.context.support.StaticWebApplicationContext;
 import org.springframework.web.cors.CorsConfiguration;
@@ -207,8 +207,7 @@ class CorsAbstractHandlerMappingTests {
 
 	private static class TestHandlerMapping extends AbstractHandlerMapping {
 
-		@Nullable
-		private CorsConfiguration savedCorsConfig;
+		private @Nullable CorsConfiguration savedCorsConfig;
 
 
 		TestHandlerMapping() {

spring-webmvc/src/test/java/org/springframework/web/servlet/handler/PathPatternsTestUtils.java

@@ -20,9 +20,9 @@ import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.stream.Stream;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Named;
 
-import org.springframework.lang.Nullable;
 import org.springframework.web.testfixture.servlet.MockHttpServletRequest;
 import org.springframework.web.util.ServletRequestPathUtils;
 import org.springframework.web.util.UrlPathHelper;

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

@@ -20,6 +20,7 @@ import java.io.IOException;
 import java.io.Writer;
 
 import jakarta.servlet.ServletException;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.aop.Pointcut;
@@ -28,7 +29,6 @@ import org.springframework.aop.interceptor.SimpleTraceInterceptor;
 import org.springframework.aop.support.DefaultPointcutAdvisor;
 import org.springframework.aop.support.annotation.AnnotationMatchingPointcut;
 import org.springframework.beans.factory.support.RootBeanDefinition;
-import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.context.WebApplicationContext;

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

@@ -20,13 +20,13 @@ import java.io.IOException;
 import java.io.Writer;
 
 import jakarta.servlet.ServletException;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator;
 import org.springframework.aop.interceptor.SimpleTraceInterceptor;
 import org.springframework.aop.support.DefaultPointcutAdvisor;
 import org.springframework.beans.factory.support.RootBeanDefinition;
-import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.context.WebApplicationContext;

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

@@ -27,6 +27,7 @@ import java.util.stream.Stream;
 
 import jakarta.servlet.ServletException;
 import jakarta.servlet.http.HttpServletRequest;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -36,7 +37,6 @@ import org.springframework.http.HttpMethod;
 import org.springframework.http.MediaType;
 import org.springframework.http.server.RequestPath;
 import org.springframework.http.server.observation.ServerRequestObservationContext;
-import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Controller;
 import org.springframework.util.AntPathMatcher;
 import org.springframework.util.MultiValueMap;

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

@@ -17,12 +17,12 @@
 package org.springframework.web.servlet.mvc.method.annotation;
 
 import jakarta.servlet.ServletException;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.context.ApplicationContextInitializer;
-import org.springframework.lang.Nullable;
 import org.springframework.web.context.WebApplicationContext;
 import org.springframework.web.context.support.GenericWebApplicationContext;
 import org.springframework.web.servlet.DispatcherServlet;
@@ -44,8 +44,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 public abstract class AbstractServletHandlerMethodTests {
 
-	@Nullable
-	private DispatcherServlet servlet;
+	private @Nullable DispatcherServlet servlet;
 
 
 	protected DispatcherServlet getServlet() {

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

@@ -26,6 +26,7 @@ import java.util.Properties;
 import java.util.stream.Stream;
 
 import jakarta.servlet.http.HttpServletRequest;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Named;
 
@@ -37,7 +38,6 @@ import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.env.PropertiesPropertySource;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.server.RequestPath;
-import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Controller;
 import org.springframework.util.AntPathMatcher;
 import org.springframework.util.CollectionUtils;
@@ -387,8 +387,7 @@ class CrossOriginTests {
 	}
 
 
-	@Nullable
-	private CorsConfiguration getCorsConfiguration(@Nullable HandlerExecutionChain chain, boolean isPreFlightRequest) {
+	private @Nullable CorsConfiguration getCorsConfiguration(@Nullable HandlerExecutionChain chain, boolean isPreFlightRequest) {
 		assertThat(chain).isNotNull();
 		if (isPreFlightRequest) {
 			Object handler = chain.getHandler();

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

@@ -21,6 +21,7 @@ import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.stream.Stream;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
@@ -32,7 +33,6 @@ import org.springframework.aop.support.StaticMethodMatcherPointcut;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.beans.propertyeditors.CustomDateEditor;
 import org.springframework.core.annotation.AnnotationUtils;
-import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;
 import org.springframework.web.bind.WebDataBinder;

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

@@ -28,6 +28,7 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 import jakarta.servlet.FilterChain;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -40,7 +41,6 @@ import org.springframework.http.converter.ByteArrayHttpMessageConverter;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
-import org.springframework.lang.Nullable;
 import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
 import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.bind.annotation.RequestMapping;

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

@@ -29,6 +29,7 @@ import java.util.Map;
 import java.util.Optional;
 
 import jakarta.servlet.http.HttpServletRequest;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -43,7 +44,6 @@ import org.springframework.format.annotation.DateTimeFormat.ISO;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
-import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Controller;
 import org.springframework.util.MultiValueMap;
 import org.springframework.web.bind.annotation.GetMapping;

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

@@ -32,6 +32,7 @@ import io.micrometer.context.ContextSnapshotFactory;
 import io.reactivex.rxjava3.core.Single;
 import io.reactivex.rxjava3.core.SingleEmitter;
 import jakarta.servlet.http.HttpServletRequest;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
@@ -48,7 +49,6 @@ import org.springframework.core.task.TaskExecutor;
 import org.springframework.http.MediaType;
 import org.springframework.http.codec.ServerSentEvent;
 import org.springframework.http.server.ServletServerHttpResponse;
-import org.springframework.lang.Nullable;
 import org.springframework.web.accept.ContentNegotiationManager;
 import org.springframework.web.accept.ContentNegotiationManagerFactoryBean;
 import org.springframework.web.context.request.NativeWebRequest;

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

@@ -39,6 +39,7 @@ import jakarta.servlet.http.Cookie;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
 import jakarta.validation.Valid;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -51,7 +52,6 @@ import org.springframework.http.CacheControl;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
-import org.springframework.lang.Nullable;
 import org.springframework.ui.Model;
 import org.springframework.ui.ModelMap;
 import org.springframework.validation.BindingResult;
@@ -639,9 +639,8 @@ class RequestMappingHandlerAdapterIntegrationTests {
 					parameter.hasParameterAnnotation(AuthenticationPrincipal.class));
 		}
 
-		@Nullable
 		@Override
-		public Object resolveArgument(
+		public @Nullable Object resolveArgument(
 				MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
 				NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) {
 

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

@@ -30,6 +30,7 @@ import java.util.Map;
 
 import jakarta.servlet.AsyncEvent;
 import org.apache.groovy.util.Maps;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -46,7 +47,6 @@ import org.springframework.http.converter.json.MappingJacksonValue;
 import org.springframework.http.server.ServerHttpRequest;
 import org.springframework.http.server.ServerHttpResponse;
 import org.springframework.http.server.ServletServerHttpResponse;
-import org.springframework.lang.Nullable;
 import org.springframework.ui.Model;
 import org.springframework.web.bind.annotation.ControllerAdvice;
 import org.springframework.web.bind.annotation.ModelAttribute;

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

@@ -29,6 +29,7 @@ import java.util.Optional;
 import jakarta.servlet.http.Part;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.NotNull;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -39,7 +40,6 @@ import org.springframework.http.HttpInputMessage;
 import org.springframework.http.MediaType;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.StringHttpMessageConverter;
-import org.springframework.lang.Nullable;
 import org.springframework.util.ReflectionUtils;
 import org.springframework.validation.BindingResult;
 import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;

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

@@ -25,6 +25,7 @@ import java.util.Optional;
 
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.NotNull;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -37,7 +38,6 @@ import org.springframework.http.HttpOutputMessage;
 import org.springframework.http.MediaType;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.HttpMessageNotReadableException;
-import org.springframework.lang.Nullable;
 import org.springframework.validation.BindingResult;
 import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
 import org.springframework.web.HttpMediaTypeNotAcceptableException;

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

@@ -30,6 +30,7 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 import com.fasterxml.jackson.annotation.JsonView;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.SerializationFeature;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.skyscreamer.jsonassert.JSONAssert;
 import org.xmlunit.assertj.XmlAssert;
@@ -53,7 +54,6 @@ import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
 import org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter;
 import org.springframework.http.converter.xml.MappingJackson2XmlHttpMessageConverter;
-import org.springframework.lang.Nullable;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.ReflectionUtils;
 import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
@@ -970,8 +970,7 @@ class RequestResponseBodyMethodProcessorTests {
 			this.withView1 = withView1;
 		}
 
-		@Nullable
-		public String getWithView2() {
+		public @Nullable String getWithView2() {
 			return withView2;
 		}
 
@@ -979,8 +978,7 @@ class RequestResponseBodyMethodProcessorTests {
 			this.withView2 = withView2;
 		}
 
-		@Nullable
-		public String getWithoutView() {
+		public @Nullable String getWithoutView() {
 			return withoutView;
 		}
 

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

@@ -58,6 +58,7 @@ import jakarta.servlet.http.Part;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.NotNull;
 import jakarta.xml.bind.annotation.XmlRootElement;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator;
@@ -97,7 +98,6 @@ import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
 import org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter;
 import org.springframework.http.converter.xml.MarshallingHttpMessageConverter;
-import org.springframework.lang.Nullable;
 import org.springframework.oxm.jaxb.Jaxb2Marshaller;
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.ExtendedModelMap;

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

@@ -23,11 +23,11 @@ import java.util.List;
 import java.util.Set;
 import java.util.function.Consumer;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.http.MediaType;
-import org.springframework.lang.Nullable;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.springframework.web.servlet.mvc.method.annotation.SseEmitter.event;

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/support/DefaultHandlerExceptionResolverTests.java

@@ -22,6 +22,7 @@ import java.util.Collections;
 
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -34,7 +35,6 @@ import org.springframework.http.MediaType;
 import org.springframework.http.converter.HttpMessageNotReadableException;
 import org.springframework.http.converter.HttpMessageNotWritableException;
 import org.springframework.http.server.ServletServerHttpRequest;
-import org.springframework.lang.Nullable;
 import org.springframework.validation.BeanPropertyBindingResult;
 import org.springframework.web.HttpMediaTypeNotSupportedException;
 import org.springframework.web.HttpRequestMethodNotSupportedException;

spring-webmvc/src/test/java/org/springframework/web/servlet/support/FlashMapManagerTests.java

@@ -27,9 +27,9 @@ import java.util.concurrent.CopyOnWriteArrayList;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
 import org.assertj.core.api.ObjectAssert;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
-import org.springframework.lang.Nullable;
 import org.springframework.web.servlet.FlashMap;
 import org.springframework.web.testfixture.servlet.MockHttpServletRequest;
 import org.springframework.web.testfixture.servlet.MockHttpServletResponse;

spring-webmvc/src/test/java/org/springframework/web/servlet/tags/AbstractTagTests.java

@@ -20,8 +20,8 @@ import jakarta.el.ELContext;
 import jakarta.servlet.ServletContext;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
+import org.jspecify.annotations.Nullable;
 
-import org.springframework.lang.Nullable;
 import org.springframework.web.context.WebApplicationContext;
 import org.springframework.web.servlet.DispatcherServlet;
 import org.springframework.web.servlet.LocaleResolver;

spring-webmvc/src/test/java/org/springframework/web/servlet/tags/form/ItemPet.java

@@ -18,7 +18,8 @@ package org.springframework.web.servlet.tags.form;
 
 import java.beans.PropertyEditorSupport;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.ObjectUtils;
 
 /**

spring-webmvc/src/test/java/org/springframework/web/servlet/tags/form/OptionTagTests.java

@@ -24,12 +24,12 @@ import java.util.List;
 
 import jakarta.servlet.jsp.tagext.BodyTag;
 import jakarta.servlet.jsp.tagext.Tag;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.propertyeditors.StringArrayPropertyEditor;
 import org.springframework.beans.testfixture.beans.Colour;
 import org.springframework.beans.testfixture.beans.TestBean;
-import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 import org.springframework.validation.BeanPropertyBindingResult;
 import org.springframework.web.servlet.support.BindStatus;