Refine null-safety in spring-webmvc

See gh-32475

Author: sdeleuze

spring-webmvc/src/main/java/org/springframework/web/servlet/config/ResourcesBeanDefinitionParser.java

@@ -86,6 +86,7 @@ class ResourcesBeanDefinitionParser implements BeanDefinitionParser {
 
 
 	@Override
+	@Nullable
 	public BeanDefinition parse(Element element, ParserContext context) {
 		Object source = context.extractSource(element);
 

spring-webmvc/src/main/java/org/springframework/web/servlet/config/ViewControllerBeanDefinitionParser.java

@@ -60,6 +60,7 @@ class ViewControllerBeanDefinitionParser implements BeanDefinitionParser {
 
 
 	@Override
+	@Nullable
 	@SuppressWarnings("unchecked")
 	public BeanDefinition parse(Element element, ParserContext parserContext) {
 		Object source = parserContext.extractSource(element);

spring-webmvc/src/main/java/org/springframework/web/servlet/config/ViewResolversBeanDefinitionParser.java

@@ -29,6 +29,7 @@
 import org.springframework.beans.factory.xml.BeanDefinitionParser;
 import org.springframework.beans.factory.xml.ParserContext;
 import org.springframework.core.Ordered;
+import org.springframework.lang.Nullable;
 import org.springframework.util.xml.DomUtils;
 import org.springframework.web.servlet.view.BeanNameViewResolver;
 import org.springframework.web.servlet.view.ContentNegotiatingViewResolver;
@@ -68,6 +69,7 @@ public class ViewResolversBeanDefinitionParser implements BeanDefinitionParser {
 
 
 	@Override
+	@Nullable
 	public BeanDefinition parse(Element element, ParserContext context) {
 		Object source = context.extractSource(element);
 		context.pushContainingComponent(new CompositeComponentDefinition(element.getTagName(), source));

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/WebMvcConfigurerComposite.java

@@ -160,6 +160,7 @@ public void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> excep
 	}
 
 	@Override
+	@Nullable
 	public Validator getValidator() {
 		Validator selected = null;
 		for (WebMvcConfigurer configurer : this.delegates) {

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

@@ -82,6 +82,7 @@ public MultiValueMap<String, Cookie> cookies() {
 	}
 
 	@Override
+	@Nullable
 	public ModelAndView writeTo(HttpServletRequest request, HttpServletResponse response,
 			Context context) throws ServletException, IOException {
 

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

@@ -264,6 +264,7 @@ public T entity() {
 		}
 
 		@Override
+		@Nullable
 		protected ModelAndView writeToInternal(HttpServletRequest servletRequest,
 				HttpServletResponse servletResponse, Context context)
 				throws ServletException, IOException {
@@ -363,6 +364,7 @@ public CompletionStageEntityResponse(HttpStatusCode statusCode, HttpHeaders head
 		}
 
 		@Override
+		@Nullable
 		protected ModelAndView writeToInternal(HttpServletRequest servletRequest, HttpServletResponse servletResponse,
 				Context context) throws ServletException, IOException {
 
@@ -416,6 +418,7 @@ public PublisherEntityResponse(HttpStatusCode statusCode, HttpHeaders headers,
 		}
 
 		@Override
+		@Nullable
 		protected ModelAndView writeToInternal(HttpServletRequest servletRequest, HttpServletResponse servletResponse,
 				Context context) throws ServletException, IOException {
 

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

@@ -35,6 +35,7 @@
 import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatusCode;
 import org.springframework.http.MediaType;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
@@ -229,6 +230,7 @@ public WriteFunctionResponse(HttpStatusCode statusCode, HttpHeaders headers, Mul
 		}
 
 		@Override
+		@Nullable
 		protected ModelAndView writeToInternal(HttpServletRequest request, HttpServletResponse response,
 				Context context) throws Exception {
 

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerMethodMapping.java

@@ -483,6 +483,7 @@ protected boolean hasCorsConfigurationSource(Object handler) {
 	}
 
 	@Override
+	@Nullable
 	protected CorsConfiguration getCorsConfiguration(Object handler, HttpServletRequest request) {
 		CorsConfiguration corsConfig = super.getCorsConfiguration(handler, request);
 		if (handler instanceof HandlerMethod handlerMethod) {
@@ -600,6 +601,7 @@ public List<T> getMappingsByDirectPath(String urlPath) {
 		/**
 		 * Return handler methods by mapping name. Thread-safe for concurrent use.
 		 */
+		@Nullable
 		public List<HandlerMethod> getHandlerMethodsByMappingName(String mappingName) {
 			return this.nameLookup.get(mappingName);
 		}

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/HandlerMappingIntrospector.java

@@ -500,6 +500,7 @@ public void setAttribute(String name, Object value) {
 		}
 
 		@Override
+		@Nullable
 		public Object getAttribute(String name) {
 			return this.attributes.get(name);
 		}
@@ -532,6 +533,7 @@ private static class LookupPathMatchableHandlerMapping implements MatchableHandl
 		}
 
 		@Override
+		@Nullable
 		public PathPatternParser getPatternParser() {
 			return this.delegate.getPatternParser();
 		}

spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/FixedLocaleResolver.java

@@ -88,6 +88,7 @@ public Locale getLocale() {
 				return getDefaultLocale();
 			}
 			@Override
+			@Nullable
 			public TimeZone getTimeZone() {
 				return getDefaultTimeZone();
 			}