Protected visibility for configurePathMatch and configureAsyncSupport

Issue: SPR-14599

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

@@ -53,8 +53,8 @@ public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
 
 
 	@Override
-	protected void addInterceptors(InterceptorRegistry registry) {
+	protected void configurePathMatch(PathMatchConfigurer configurer) {
-		this.configurers.addInterceptors(registry);
+		this.configurers.configurePathMatch(configurer);
 	}
 
 	@Override
@@ -63,13 +63,33 @@ public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
 	}
 
 	@Override
-	public void configureAsyncSupport(AsyncSupportConfigurer configurer) {
+	protected void configureAsyncSupport(AsyncSupportConfigurer configurer) {
 		this.configurers.configureAsyncSupport(configurer);
 	}
 
 	@Override
-	public void configurePathMatch(PathMatchConfigurer configurer) {
+	protected void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
-		this.configurers.configurePathMatch(configurer);
+		this.configurers.configureDefaultServletHandling(configurer);
+	}
+
+	@Override
+	protected void addFormatters(FormatterRegistry registry) {
+		this.configurers.addFormatters(registry);
+	}
+
+	@Override
+	protected void addInterceptors(InterceptorRegistry registry) {
+		this.configurers.addInterceptors(registry);
+	}
+
+	@Override
+	protected void addResourceHandlers(ResourceHandlerRegistry registry) {
+		this.configurers.addResourceHandlers(registry);
+	}
+
+	@Override
+	protected void addCorsMappings(CorsRegistry registry) {
+		this.configurers.addCorsMappings(registry);
 	}
 
 	@Override
@@ -82,16 +102,6 @@ public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
 		this.configurers.configureViewResolvers(registry);
 	}
 
-	@Override
-	protected void addResourceHandlers(ResourceHandlerRegistry registry) {
-		this.configurers.addResourceHandlers(registry);
-	}
-
-	@Override
-	protected void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
-		this.configurers.configureDefaultServletHandling(configurer);
-	}
-
 	@Override
 	protected void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
 		this.configurers.addArgumentResolvers(argumentResolvers);
@@ -113,8 +123,13 @@ public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
 	}
 
 	@Override
-	protected void addFormatters(FormatterRegistry registry) {
+	protected void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
-		this.configurers.addFormatters(registry);
+		this.configurers.configureHandlerExceptionResolvers(exceptionResolvers);
+	}
+
+	@Override
+	protected void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
+		this.configurers.extendHandlerExceptionResolvers(exceptionResolvers);
 	}
 
 	@Override
@@ -127,19 +142,4 @@ public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
 		return this.configurers.getMessageCodesResolver();
 	}
 
-	@Override
-	protected void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
-		this.configurers.configureHandlerExceptionResolvers(exceptionResolvers);
-	}
-
-	@Override
-	protected void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
-		this.configurers.extendHandlerExceptionResolvers(exceptionResolvers);
-	}
-
-	@Override
-	protected void addCorsMappings(CorsRegistry registry) {
-		this.configurers.addCorsMappings(registry);
-	}
-
 }

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

@@ -17,13 +17,13 @@
 package org.springframework.web.servlet.config.annotation;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import javax.servlet.ServletContext;
 import javax.servlet.http.HttpServletRequest;
-import javax.xml.transform.Source;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 
@@ -86,10 +86,8 @@ import org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionRes
 import org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver;
 import org.springframework.web.servlet.mvc.method.annotation.JsonViewRequestBodyAdvice;
 import org.springframework.web.servlet.mvc.method.annotation.JsonViewResponseBodyAdvice;
-import org.springframework.web.servlet.mvc.method.annotation.RequestBodyAdvice;
 import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter;
 import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;
-import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;
 import org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver;
 import org.springframework.web.servlet.resource.ResourceUrlProvider;
 import org.springframework.web.servlet.resource.ResourceUrlProviderExposingInterceptor;
@@ -233,6 +231,7 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 		return this.servletContext;
 	}
 
+
 	/**
 	 * Return a {@link RequestMappingHandlerMapping} ordered at 0 for mapping
 	 * requests to annotated controllers.
@@ -255,11 +254,13 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 		if (configurer.isUseTrailingSlashMatch() != null) {
 			handlerMapping.setUseTrailingSlashMatch(configurer.isUseTrailingSlashMatch());
 		}
-		if (configurer.getPathMatcher() != null) {
+		UrlPathHelper pathHelper = configurer.getUrlPathHelper();
-			handlerMapping.setPathMatcher(configurer.getPathMatcher());
+		if (pathHelper != null) {
+			handlerMapping.setUrlPathHelper(pathHelper);
 		}
-		if (configurer.getUrlPathHelper() != null) {
+		PathMatcher pathMatcher = configurer.getPathMatcher();
-			handlerMapping.setUrlPathHelper(configurer.getUrlPathHelper());
+		if (pathMatcher != null) {
+			handlerMapping.setPathMatcher(pathMatcher);
 		}
 
 		return handlerMapping;
@@ -315,7 +316,7 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 	 * @see PathMatchConfigurer
 	 * @since 4.0.3
 	 */
-	public void configurePathMatch(PathMatchConfigurer configurer) {
+	protected void configurePathMatch(PathMatchConfigurer configurer) {
 	}
 
 	/**
@@ -339,7 +340,7 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 	}
 
 	protected Map<String, MediaType> getDefaultMediaTypes() {
-		Map<String, MediaType> map = new HashMap<>();
+		Map<String, MediaType> map = new HashMap<>(4);
 		if (romePresent) {
 			map.put("atom", MediaType.APPLICATION_ATOM_XML);
 			map.put("rss", MediaType.valueOf("application/rss+xml"));
@@ -487,18 +488,12 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 		adapter.setCustomReturnValueHandlers(getReturnValueHandlers());
 
 		if (jackson2Present) {
-			List<RequestBodyAdvice> requestBodyAdvices = new ArrayList<>();
+			adapter.setRequestBodyAdvice(Collections.singletonList(new JsonViewRequestBodyAdvice()));
-			requestBodyAdvices.add(new JsonViewRequestBodyAdvice());
+			adapter.setResponseBodyAdvice(Collections.singletonList(new JsonViewResponseBodyAdvice()));
-			adapter.setRequestBodyAdvice(requestBodyAdvices);
-
-			List<ResponseBodyAdvice<?>> responseBodyAdvices = new ArrayList<>();
-			responseBodyAdvices.add(new JsonViewResponseBodyAdvice());
-			adapter.setResponseBodyAdvice(responseBodyAdvices);
 		}
 
 		AsyncSupportConfigurer configurer = new AsyncSupportConfigurer();
 		configureAsyncSupport(configurer);
-
 		if (configurer.getTaskExecutor() != null) {
 			adapter.setTaskExecutor(configurer.getTaskExecutor());
 		}
@@ -531,6 +526,20 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 		return initializer;
 	}
 
+	/**
+	 * Override this method to provide a custom {@link MessageCodesResolver}.
+	 */
+	protected MessageCodesResolver getMessageCodesResolver() {
+		return null;
+	}
+
+	/**
+	 * Override this method to configure asynchronous request processing options.
+	 * @see AsyncSupportConfigurer
+	 */
+	protected void configureAsyncSupport(AsyncSupportConfigurer configurer) {
+	}
+
 	/**
 	 * Return a {@link FormattingConversionService} for use with annotated
 	 * controller methods and the {@code spring:eval} JSP tag.
@@ -543,6 +552,12 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 		return conversionService;
 	}
 
+	/**
+	 * Override this method to add custom {@link Converter}s and {@link Formatter}s.
+	 */
+	protected void addFormatters(FormatterRegistry registry) {
+	}
+
 	/**
 	 * Return a global {@link Validator} instance for example for validating
 	 * {@code @ModelAttribute} and {@code @RequestBody} method arguments.
@@ -576,6 +591,13 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 		return validator;
 	}
 
+	/**
+	 * Override this method to provide a custom {@link Validator}.
+	 */
+	protected Validator getValidator() {
+		return null;
+	}
+
 	/**
 	 * Return a global {@link PathMatcher} instance for path matching
 	 * patterns in {@link HandlerMapping}s.
@@ -602,26 +624,8 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 	 */
 	@Bean
 	public UrlPathHelper mvcUrlPathHelper() {
-		if (getPathMatchConfigurer().getUrlPathHelper() != null) {
+		UrlPathHelper pathHelper = getPathMatchConfigurer().getUrlPathHelper();
-			return getPathMatchConfigurer().getUrlPathHelper();
+		return (pathHelper != null ? pathHelper : new UrlPathHelper());
-		}
-		else {
-			return new UrlPathHelper();
-		}
-	}
-
-	/**
-	 * Override this method to provide a custom {@link Validator}.
-	 */
-	protected Validator getValidator() {
-		return null;
-	}
-
-	/**
-	 * Override this method to provide a custom {@link MessageCodesResolver}.
-	 */
-	protected MessageCodesResolver getMessageCodesResolver() {
-		return null;
 	}
 
 	/**
@@ -762,19 +766,6 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 		}
 	}
 
-	/**
-	 * Override this method to add custom {@link Converter}s and {@link Formatter}s.
-	 */
-	protected void addFormatters(FormatterRegistry registry) {
-	}
-
-	/**
-	 * Override this method to configure asynchronous request processing options.
-	 * @see AsyncSupportConfigurer
-	 */
-	public void configureAsyncSupport(AsyncSupportConfigurer configurer) {
-	}
-
 	/**
 	 * Return an instance of {@link CompositeUriComponentsContributor} for use with
 	 * {@link org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder}.
@@ -817,11 +808,9 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 	public HandlerExceptionResolver handlerExceptionResolver() {
 		List<HandlerExceptionResolver> exceptionResolvers = new ArrayList<>();
 		configureHandlerExceptionResolvers(exceptionResolvers);
-
 		if (exceptionResolvers.isEmpty()) {
 			addDefaultHandlerExceptionResolvers(exceptionResolvers);
 		}
-
 		extendHandlerExceptionResolvers(exceptionResolvers);
 		HandlerExceptionResolverComposite composite = new HandlerExceptionResolverComposite();
 		composite.setOrder(0);
@@ -871,9 +860,8 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 		exceptionHandlerResolver.setCustomArgumentResolvers(getArgumentResolvers());
 		exceptionHandlerResolver.setCustomReturnValueHandlers(getReturnValueHandlers());
 		if (jackson2Present) {
-			List<ResponseBodyAdvice<?>> interceptors = new ArrayList<>();
+			exceptionHandlerResolver.setResponseBodyAdvice(
-			interceptors.add(new JsonViewResponseBodyAdvice());
+					Collections.singletonList(new JsonViewResponseBodyAdvice()));
-			exceptionHandlerResolver.setResponseBodyAdvice(interceptors);
 		}
 		exceptionHandlerResolver.setApplicationContext(this.applicationContext);
 		exceptionHandlerResolver.afterPropertiesSet();

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

@@ -46,12 +46,104 @@ import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandl
  */
 public interface WebMvcConfigurer {
 
+	/**
+	 * Helps with configuring HandlerMappings path matching options such as trailing slash match,
+	 * suffix registration, path matcher and path helper.
+	 * Configured path matcher and path helper instances are shared for:
+	 * <ul>
+	 * <li>RequestMappings</li>
+	 * <li>ViewControllerMappings</li>
+	 * <li>ResourcesMappings</li>
+	 * </ul>
+	 * @since 4.0.3
+	 */
+	void configurePathMatch(PathMatchConfigurer configurer);
+
+	/**
+	 * Configure content negotiation options.
+	 */
+	void configureContentNegotiation(ContentNegotiationConfigurer configurer);
+
+	/**
+	 * Configure asynchronous request handling options.
+	 */
+	void configureAsyncSupport(AsyncSupportConfigurer configurer);
+
+	/**
+	 * Configure a handler to delegate unhandled requests by forwarding to the
+	 * Servlet container's "default" servlet. A common use case for this is when
+	 * the {@link DispatcherServlet} is mapped to "/" thus overriding the
+	 * Servlet container's default handling of static resources.
+	 */
+	void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer);
+
 	/**
 	 * Add {@link Converter}s and {@link Formatter}s in addition to the ones
 	 * registered by default.
 	 */
 	void addFormatters(FormatterRegistry registry);
 
+	/**
+	 * Add Spring MVC lifecycle interceptors for pre- and post-processing of
+	 * controller method invocations. Interceptors can be registered to apply
+	 * to all requests or be limited to a subset of URL patterns.
+	 * <p><strong>Note</strong> that interceptors registered here only apply to
+	 * controllers and not to resource handler requests. To intercept requests for
+	 * static resources either declare a
+	 * {@link org.springframework.web.servlet.handler.MappedInterceptor MappedInterceptor}
+	 * bean or switch to advanced configuration mode by extending
+	 * {@link org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport
+	 * WebMvcConfigurationSupport} and then override {@code resourceHandlerMapping}.
+	 */
+	void addInterceptors(InterceptorRegistry registry);
+
+	/**
+	 * Add handlers to serve static resources such as images, js, and, css
+	 * files from specific locations under web application root, the classpath,
+	 * and others.
+	 */
+	void addResourceHandlers(ResourceHandlerRegistry registry);
+
+	/**
+	 * Configure cross origin requests processing.
+	 * @since 4.2
+	 */
+	void addCorsMappings(CorsRegistry registry);
+
+	/**
+	 * Configure simple automated controllers pre-configured with the response
+	 * status code and/or a view to render the response body. This is useful in
+	 * cases where there is no need for custom controller logic -- e.g. render a
+	 * home page, perform simple site URL redirects, return a 404 status with
+	 * HTML content, a 204 with no content, and more.
+	 */
+	void addViewControllers(ViewControllerRegistry registry);
+
+	/**
+	 * Configure view resolvers to translate String-based view names returned from
+	 * controllers into concrete {@link org.springframework.web.servlet.View}
+	 * implementations to perform rendering with.
+	 */
+	void configureViewResolvers(ViewResolverRegistry registry);
+
+	/**
+	 * Add resolvers to support custom controller method argument types.
+	 * <p>This does not override the built-in support for resolving handler
+	 * method arguments. To customize the built-in support for argument
+	 * resolution, configure {@link RequestMappingHandlerAdapter} directly.
+	 * @param argumentResolvers initially an empty list
+	 */
+	void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers);
+
+	/**
+	 * Add handlers to support custom controller method return value types.
+	 * <p>Using this option does not override the built-in support for handling
+	 * return values. To customize the built-in support for handling return
+	 * values, configure RequestMappingHandlerAdapter directly.
+	 * @param returnValueHandlers initially an empty list
+	 */
+	void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers);
+
 	/**
 	 * Configure the {@link HttpMessageConverter}s to use for reading or writing
 	 * to the body of the request or response. If no converters are added, a
@@ -73,55 +165,6 @@ public interface WebMvcConfigurer {
 	 */
 	void extendMessageConverters(List<HttpMessageConverter<?>> converters);
 
-	/**
-	 * Provide a custom {@link Validator} instead of the one created by default.
-	 * The default implementation, assuming JSR-303 is on the classpath, is:
-	 * {@link org.springframework.validation.beanvalidation.OptionalValidatorFactoryBean}.
-	 * Leave the return value as {@code null} to keep the default.
-	 */
-	Validator getValidator();
-
-	/**
-	 * Configure content negotiation options.
-	 */
-	void configureContentNegotiation(ContentNegotiationConfigurer configurer);
-
-	/**
-	 * Configure asynchronous request handling options.
-	 */
-	void configureAsyncSupport(AsyncSupportConfigurer configurer);
-
-	/**
-	 * Helps with configuring HandlerMappings path matching options such as trailing slash match,
-	 * suffix registration, path matcher and path helper.
-	 * Configured path matcher and path helper instances are shared for:
-	 * <ul>
-	 * <li>RequestMappings</li>
-	 * <li>ViewControllerMappings</li>
-	 * <li>ResourcesMappings</li>
-	 * </ul>
-	 * @since 4.0.3
-	 */
-	void configurePathMatch(PathMatchConfigurer configurer);
-
-	/**
-	 * Add resolvers to support custom controller method argument types.
-	 * <p>This does not override the built-in support for resolving handler
-	 * method arguments. To customize the built-in support for argument
-	 * resolution, configure {@link RequestMappingHandlerAdapter} directly.
-	 * @param argumentResolvers initially an empty list
-	 */
-	void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers);
-
-	/**
-	 * Add handlers to support custom controller method return value types.
-	 * <p>Using this option does not override the built-in support for handling
-	 * return values. To customize the built-in support for handling return
-	 * values, configure RequestMappingHandlerAdapter directly.
-	 * @param returnValueHandlers initially an empty list
-	 */
-	void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers);
-
 	/**
 	 * Configure the {@link HandlerExceptionResolver}s to handle unresolved
 	 * controller exceptions. If no resolvers are added to the list, default
@@ -140,18 +183,12 @@ public interface WebMvcConfigurer {
 	void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers);
 
 	/**
-	 * Add Spring MVC lifecycle interceptors for pre- and post-processing of
+	 * Provide a custom {@link Validator} instead of the one created by default.
-	 * controller method invocations. Interceptors can be registered to apply
+	 * The default implementation, assuming JSR-303 is on the classpath, is:
-	 * to all requests or be limited to a subset of URL patterns.
+	 * {@link org.springframework.validation.beanvalidation.OptionalValidatorFactoryBean}.
-	 * <p><strong>Note</strong> that interceptors registered here only apply to
+	 * Leave the return value as {@code null} to keep the default.
-	 * controllers and not to resource handler requests. To intercept requests for
-	 * static resources either declare a
-	 * {@link org.springframework.web.servlet.handler.MappedInterceptor MappedInterceptor}
-	 * bean or switch to advanced configuration mode by extending
-	 * {@link org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport
-	 * WebMvcConfigurationSupport} and then override {@code resourceHandlerMapping}.
 	 */
-	void addInterceptors(InterceptorRegistry registry);
+	Validator getValidator();
 
 	/**
 	 * Provide a custom {@link MessageCodesResolver} for building message codes
@@ -160,41 +197,4 @@ public interface WebMvcConfigurer {
 	 */
 	MessageCodesResolver getMessageCodesResolver();
 
-	/**
-	 * Configure simple automated controllers pre-configured with the response
-	 * status code and/or a view to render the response body. This is useful in
-	 * cases where there is no need for custom controller logic -- e.g. render a
-	 * home page, perform simple site URL redirects, return a 404 status with
-	 * HTML content, a 204 with no content, and more.
-	 */
-	void addViewControllers(ViewControllerRegistry registry);
-
-	/**
-	 * Configure view resolvers to translate String-based view names returned from
-	 * controllers into concrete {@link org.springframework.web.servlet.View}
-	 * implementations to perform rendering with.
-	 */
-	void configureViewResolvers(ViewResolverRegistry registry);
-
-	/**
-	 * Add handlers to serve static resources such as images, js, and, css
-	 * files from specific locations under web application root, the classpath,
-	 * and others.
-	 */
-	void addResourceHandlers(ResourceHandlerRegistry registry);
-
-	/**
-	 * Configure a handler to delegate unhandled requests by forwarding to the
-	 * Servlet container's "default" servlet. A common use case for this is when
-	 * the {@link DispatcherServlet} is mapped to "/" thus overriding the
-	 * Servlet container's default handling of static resources.
-	 */
-	void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer);
-
-	/**
-	 * Configure cross origin requests processing.
-	 * @since 4.2
-	 */
-	void addCorsMappings(CorsRegistry registry);
-
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,7 +28,7 @@ import org.springframework.web.servlet.HandlerExceptionResolver;
 
 /**
  * An implementation of {@link WebMvcConfigurer} with empty methods allowing
- * sub-classes to override only the methods they're interested in.
+ * subclasses to override only the methods they're interested in.
  *
  * @author Rossen Stoyanchev
  * @since 3.1
@@ -40,32 +40,7 @@ public abstract class WebMvcConfigurerAdapter implements WebMvcConfigurer {
 	 * <p>This implementation is empty.
 	 */
 	@Override
-	public void addFormatters(FormatterRegistry registry) {
+	public void configurePathMatch(PathMatchConfigurer configurer) {
-	}
-
-	/**
-	 * {@inheritDoc}
-	 * <p>This implementation is empty.
-	 */
-	@Override
-	public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
-	}
-
-	/**
-	 * {@inheritDoc}
-	 * <p>This implementation is empty.
-	 */
-	@Override
-	public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
-	}
-
-	/**
-	 * {@inheritDoc}
-	 * <p>This implementation returns {@code null}
-	 */
-	@Override
-	public Validator getValidator() {
-		return null;
 	}
 
 	/**
@@ -89,7 +64,7 @@ public abstract class WebMvcConfigurerAdapter implements WebMvcConfigurer {
 	 * <p>This implementation is empty.
 	 */
 	@Override
-	public void configurePathMatch(PathMatchConfigurer configurer) {
+	public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
 	}
 
 	/**
@@ -97,40 +72,7 @@ public abstract class WebMvcConfigurerAdapter implements WebMvcConfigurer {
 	 * <p>This implementation is empty.
 	 */
 	@Override
-	public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
+	public void addFormatters(FormatterRegistry registry) {
-	}
-
-	/**
-	 * {@inheritDoc}
-	 * <p>This implementation is empty.
-	 */
-	@Override
-	public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
-	}
-
-	/**
-	 * {@inheritDoc}
-	 * <p>This implementation is empty.
-	 */
-	@Override
-	public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
-	}
-
-	/**
-	 * {@inheritDoc}
-	 * <p>This implementation is empty.
-	 */
-	@Override
-	public void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
-	}
-
-	/**
-	 * {@inheritDoc}
-	 * <p>This implementation is empty.
-	 */
-	@Override
-	public MessageCodesResolver getMessageCodesResolver() {
-		return null;
 	}
 
 	/**
@@ -141,6 +83,22 @@ public abstract class WebMvcConfigurerAdapter implements WebMvcConfigurer {
 	public void addInterceptors(InterceptorRegistry registry) {
 	}
 
+	/**
+	 * {@inheritDoc}
+	 * <p>This implementation is empty.
+	 */
+	@Override
+	public void addResourceHandlers(ResourceHandlerRegistry registry) {
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * <p>This implementation is empty.
+	 */
+	@Override
+	public void addCorsMappings(CorsRegistry registry) {
+	}
+
 	/**
 	 * {@inheritDoc}
 	 * <p>This implementation is empty.
@@ -162,7 +120,7 @@ public abstract class WebMvcConfigurerAdapter implements WebMvcConfigurer {
 	 * <p>This implementation is empty.
 	 */
 	@Override
-	public void addResourceHandlers(ResourceHandlerRegistry registry) {
+	public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
 	}
 
 	/**
@@ -170,7 +128,7 @@ public abstract class WebMvcConfigurerAdapter implements WebMvcConfigurer {
 	 * <p>This implementation is empty.
 	 */
 	@Override
-	public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
+	public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
 	}
 
 	/**
@@ -178,7 +136,49 @@ public abstract class WebMvcConfigurerAdapter implements WebMvcConfigurer {
 	 * <p>This implementation is empty.
 	 */
 	@Override
-	public void addCorsMappings(CorsRegistry registry) {
+	public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * <p>This implementation is empty.
+	 */
+	@Override
+	public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * <p>This implementation is empty.
+	 */
+	@Override
+	public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * <p>This implementation is empty.
+	 */
+	@Override
+	public void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * <p>This implementation returns {@code null}.
+	 */
+	@Override
+	public Validator getValidator() {
+		return null;
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * <p>This implementation returns {@code null}.
+	 */
+	@Override
+	public MessageCodesResolver getMessageCodesResolver() {
+		return null;
 	}
 
 }

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

@@ -21,6 +21,7 @@ import java.util.List;
 
 import org.springframework.format.FormatterRegistry;
 import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.util.CollectionUtils;
 import org.springframework.validation.MessageCodesResolver;
 import org.springframework.validation.Validator;
 import org.springframework.web.method.support.HandlerMethodArgumentResolver;
@@ -35,18 +36,20 @@ import org.springframework.web.servlet.HandlerExceptionResolver;
  */
 class WebMvcConfigurerComposite implements WebMvcConfigurer {
 
-	private final List<WebMvcConfigurer> delegates = new ArrayList<>();
+	private final List<WebMvcConfigurer> delegates = new ArrayList<WebMvcConfigurer>();
+
 
 	public void addWebMvcConfigurers(List<WebMvcConfigurer> configurers) {
-		if (configurers != null) {
+		if (!CollectionUtils.isEmpty(configurers)) {
 			this.delegates.addAll(configurers);
 		}
 	}
 
+
 	@Override
-	public void addFormatters(FormatterRegistry registry) {
+	public void configurePathMatch(PathMatchConfigurer configurer) {
 		for (WebMvcConfigurer delegate : this.delegates) {
-			delegate.addFormatters(registry);
+			delegate.configurePathMatch(configurer);
 		}
 	}
 
@@ -65,51 +68,16 @@ class WebMvcConfigurerComposite implements WebMvcConfigurer {
 	}
 
 	@Override
-	public void configurePathMatch(PathMatchConfigurer configurer) {
+	public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
 		for (WebMvcConfigurer delegate : this.delegates) {
-			delegate.configurePathMatch(configurer);
+			delegate.configureDefaultServletHandling(configurer);
 		}
 	}
 
 	@Override
-	public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
+	public void addFormatters(FormatterRegistry registry) {
 		for (WebMvcConfigurer delegate : this.delegates) {
-			delegate.configureMessageConverters(converters);
+			delegate.addFormatters(registry);
-		}
-	}
-
-	@Override
-	public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
-		for (WebMvcConfigurer delegate : this.delegates) {
-			delegate.extendMessageConverters(converters);
-		}
-	}
-
-	@Override
-	public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
-		for (WebMvcConfigurer delegate : this.delegates) {
-			delegate.addArgumentResolvers(argumentResolvers);
-		}
-	}
-
-	@Override
-	public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
-		for (WebMvcConfigurer delegate : this.delegates) {
-			delegate.addReturnValueHandlers(returnValueHandlers);
-		}
-	}
-
-	@Override
-	public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
-		for (WebMvcConfigurer delegate : this.delegates) {
-			delegate.configureHandlerExceptionResolvers(exceptionResolvers);
-		}
-	}
-
-	@Override
-	public void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
-		for (WebMvcConfigurer delegate : this.delegates) {
-			delegate.extendHandlerExceptionResolvers(exceptionResolvers);
 		}
 	}
 
@@ -120,6 +88,20 @@ class WebMvcConfigurerComposite implements WebMvcConfigurer {
 		}
 	}
 
+	@Override
+	public void addResourceHandlers(ResourceHandlerRegistry registry) {
+		for (WebMvcConfigurer delegate : this.delegates) {
+			delegate.addResourceHandlers(registry);
+		}
+	}
+
+	@Override
+	public void addCorsMappings(CorsRegistry registry) {
+		for (WebMvcConfigurer delegate : this.delegates) {
+			delegate.addCorsMappings(registry);
+		}
+	}
+
 	@Override
 	public void addViewControllers(ViewControllerRegistry registry) {
 		for (WebMvcConfigurer delegate : this.delegates) {
@@ -135,61 +117,77 @@ class WebMvcConfigurerComposite implements WebMvcConfigurer {
 	}
 
 	@Override
-	public void addResourceHandlers(ResourceHandlerRegistry registry) {
+	public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
 		for (WebMvcConfigurer delegate : this.delegates) {
-			delegate.addResourceHandlers(registry);
+			delegate.addArgumentResolvers(argumentResolvers);
 		}
 	}
 
 	@Override
-	public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
+	public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
 		for (WebMvcConfigurer delegate : this.delegates) {
-			delegate.configureDefaultServletHandling(configurer);
+			delegate.addReturnValueHandlers(returnValueHandlers);
+		}
+	}
+
+	@Override
+	public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
+		for (WebMvcConfigurer delegate : this.delegates) {
+			delegate.configureMessageConverters(converters);
+		}
+	}
+
+	@Override
+	public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
+		for (WebMvcConfigurer delegate : this.delegates) {
+			delegate.extendMessageConverters(converters);
+		}
+	}
+
+	@Override
+	public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
+		for (WebMvcConfigurer delegate : this.delegates) {
+			delegate.configureHandlerExceptionResolvers(exceptionResolvers);
+		}
+	}
+
+	@Override
+	public void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
+		for (WebMvcConfigurer delegate : this.delegates) {
+			delegate.extendHandlerExceptionResolvers(exceptionResolvers);
 		}
 	}
 
 	@Override
 	public Validator getValidator() {
-		List<Validator> candidates = new ArrayList<>();
+		Validator selected = null;
 		for (WebMvcConfigurer configurer : this.delegates) {
 			Validator validator = configurer.getValidator();
 			if (validator != null) {
-				candidates.add(validator);
+				if (selected != null) {
+					throw new IllegalStateException("No unique Validator found: {" +
+							selected + ", " + validator + "}");
+				}
+				selected = validator;
 			}
 		}
-		return selectSingleInstance(candidates, Validator.class);
+		return selected;
-	}
-
-	@Override
-	public void addCorsMappings(CorsRegistry registry) {
-		for (WebMvcConfigurer delegate : this.delegates) {
-			delegate.addCorsMappings(registry);
-		}
-	}
-
-	private <T> T selectSingleInstance(List<T> instances, Class<T> instanceType) {
-		if (instances.size() > 1) {
-			throw new IllegalStateException(
-					"Only one [" + instanceType + "] was expected but multiple instances were provided: " + instances);
-		}
-		else if (instances.size() == 1) {
-			return instances.get(0);
-		}
-		else {
-			return null;
-		}
 	}
 
 	@Override
 	public MessageCodesResolver getMessageCodesResolver() {
-		List<MessageCodesResolver> candidates = new ArrayList<>();
+		MessageCodesResolver selected = null;
 		for (WebMvcConfigurer configurer : this.delegates) {
 			MessageCodesResolver messageCodesResolver = configurer.getMessageCodesResolver();
 			if (messageCodesResolver != null) {
-				candidates.add(messageCodesResolver);
+				if (selected != null) {
+					throw new IllegalStateException("No unique MessageCodesResolver found: {" +
+							selected + ", " + messageCodesResolver + "}");
+				}
+				selected = messageCodesResolver;
 			}
 		}
-		return selectSingleInstance(candidates, MessageCodesResolver.class);
+		return selected;
 	}
 
 }