Log warning if @RequestMapping method has no explicit mapping

Commit c0b52d09f5 introduced support for
throwing an exception if a @RequestMapping handler method in a Spring
MVC controller was mapped to an empty path. This had negative side
effects for applications that intentionally mapped to an empty path,
potentially alongside a mapping to an explicit path for the same
handler method.

This commit addresses this by logging a warning (instead of throwing an
exception) if a @RequestMapping method is mapped only to empty paths.

This commit also introduces the same support for WebFlux-based
@RequestMapping handler methods.

Closes gh-22543

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/HandlerMethodMappingTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -17,7 +17,9 @@
 package org.springframework.web.reactive.result.method;
 
 import java.lang.reflect.Method;
+import java.util.Collections;
 import java.util.Comparator;
+import java.util.Set;
 
 import org.hamcrest.Matchers;
 import org.junit.Before;
@@ -44,6 +46,7 @@ import static org.junit.Assert.assertThat;
  * Unit tests for {@link AbstractHandlerMethodMapping}.
  *
  * @author Rossen Stoyanchev
+ * @author Sam Brannen
  */
 public class HandlerMethodMappingTests {
 
@@ -155,6 +158,11 @@ public class HandlerMethodMappingTests {
 			return methodName.startsWith("handler") ? methodName : null;
 		}
 
+		@Override
+		protected Set<String> getMappingPathPatterns(String mapping) {
+			return Collections.emptySet();
+		}
+		
 		@Override
 		protected String getMatchingMapping(String pattern, ServerWebExchange exchange) {
 			PathContainer lookupPath = exchange.getRequest().getPath().pathWithinApplication();
@@ -182,4 +190,5 @@ public class HandlerMethodMappingTests {
 		public void handlerMethod2() {
 		}
 	}
+
 }

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/RequestMappingInfoHandlerMappingTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -26,6 +26,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.function.Consumer;
+import java.util.stream.Collectors;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -69,7 +70,9 @@ import static org.springframework.web.reactive.result.method.RequestMappingInfo.
 
 /**
  * Unit tests for {@link RequestMappingInfoHandlerMapping}.
+ *
  * @author Rossen Stoyanchev
+ * @author Sam Brannen
  */
 public class RequestMappingInfoHandlerMappingTests {
 
@@ -475,6 +478,11 @@ public class RequestMappingInfoHandlerMappingTests {
 				return null;
 			}
 		}
+
+		@Override
+		protected Set<String> getMappingPathPatterns(RequestMappingInfo info) {
+			return info.getPatternsCondition().getPatterns().stream().map(PathPattern::getPatternString).collect(Collectors.toSet());
+		}
 	}
 
 }