Add info on intercepting static resource requests

Issue: SPR-10655

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

@@ -134,6 +134,13 @@ public interface WebMvcConfigurer {
 	 * 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);
 

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

@@ -21,8 +21,16 @@ import org.springframework.web.context.request.WebRequestInterceptor;
 import org.springframework.web.servlet.HandlerInterceptor;
 
 /**
- * Holds information about a HandlerInterceptor mapped to a path into the application.
- * Provides a method to match a request path to the mapped path patterns.
+ * Contains a {@link HandlerInterceptor} along with include (and optionally
+ * exclude) path patterns to which the interceptor should apply. Also provides
+ * matching logic to test if the interceptor applies to a given request path.
+ *
+ * <p>A MappedInterceptor can be registered directly with any
+ * {@link org.springframework.web.servlet.handler.AbstractHandlerMethodMapping
+ * AbstractHandlerMethodMapping}. Furthermore, beans of type MappedInterceptor
+ * are automatically detected by {@code AbstractHandlerMethodMapping} (including
+ * ancestor ApplicationContext's) which effectively means the interceptor is
+ * registered "globally" with all handler mappings.
  *
  * @author Keith Donald
  * @author Rossen Stoyanchev