Reject mixed @⁠RequestMapping and @⁠HttpExchange declarations in MVC & WebFlux

This commit updates the RequestMappingHandlerMapping implementations in
Spring MVC and Spring WebFlux so that mixed @⁠RequestMapping and
@⁠HttpExchange declarations on the same element are rejected.

Note, however, that a @⁠Controller class which implements an interface
annotated with @⁠HttpExchange annotations can still inherit the
@⁠HttpExchange declarations from the interface or optionally override
them locally with @⁠HttpExchange or @⁠RequestMapping annotations.

See gh-31962
See gh-32049
Closes gh-32065

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/RequestMappingHandlerMapping.java

@@ -25,6 +25,7 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.function.Predicate;
+import java.util.stream.Stream;
 
 import org.springframework.context.EmbeddedValueResolverAware;
 import org.springframework.core.annotation.AnnotatedElementUtils;
@@ -186,6 +187,7 @@ public class RequestMappingHandlerMapping extends RequestMappingInfoHandlerMappi
 
 	@Nullable
 	private RequestMappingInfo createRequestMappingInfo(AnnotatedElement element) {
+		RequestMappingInfo requestMappingInfo = null;
 		RequestCondition<?> customCondition = (element instanceof Class<?> clazz ?
 				getCustomTypeCondition(clazz) : getCustomMethodCondition((Method) element));
 
@@ -199,19 +201,22 @@ public class RequestMappingHandlerMapping extends RequestMappingInfoHandlerMappi
 				logger.warn("Multiple @RequestMapping annotations found on %s, but only the first will be used: %s"
 						.formatted(element, requestMappings));
 			}
-			return createRequestMappingInfo(requestMappings.get(0).annotation, customCondition);
+			requestMappingInfo = createRequestMappingInfo(requestMappings.get(0).annotation, customCondition);
 		}
 
 		List<AnnotationDescriptor<HttpExchange>> httpExchanges = getAnnotationDescriptors(
 				mergedAnnotations, HttpExchange.class);
 		if (!httpExchanges.isEmpty()) {
+			Assert.state(requestMappingInfo == null,
+					() -> "%s is annotated with @RequestMapping and @HttpExchange annotations, but only one is allowed: %s"
+							.formatted(element, Stream.of(requestMappings, httpExchanges).flatMap(List::stream).toList()));
 			Assert.state(httpExchanges.size() == 1,
 					() -> "Multiple @HttpExchange annotations found on %s, but only one is allowed: %s"
 							.formatted(element, httpExchanges));
-			return createRequestMappingInfo(httpExchanges.get(0).annotation, customCondition);
+			requestMappingInfo = createRequestMappingInfo(httpExchanges.get(0).annotation, customCondition);
 		}
 
-		return null;
+		return requestMappingInfo;
 	}
 
 	/**

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

@@ -188,6 +188,40 @@ class RequestMappingHandlerMappingTests {
 				);
 	}
 
+	@Test  // gh-32065
+	void httpExchangeWithMixedAnnotationsAtClassLevel() throws NoSuchMethodException {
+		this.handlerMapping.afterPropertiesSet();
+
+		Class<?> controllerClass = MixedClassLevelAnnotationsController.class;
+		Method method = controllerClass.getDeclaredMethod("post");
+
+		assertThatIllegalStateException()
+				.isThrownBy(() -> this.handlerMapping.getMappingForMethod(method, controllerClass))
+				.withMessageContainingAll(
+					controllerClass.getName(),
+					"is annotated with @RequestMapping and @HttpExchange annotations, but only one is allowed:",
+					"@" + RequestMapping.class.getName(),
+					"@" + HttpExchange.class.getName()
+				);
+	}
+
+	@Test  // gh-32065
+	void httpExchangeWithMixedAnnotationsAtMethodLevel() throws NoSuchMethodException {
+		this.handlerMapping.afterPropertiesSet();
+
+		Class<?> controllerClass = MixedMethodLevelAnnotationsController.class;
+		Method method = controllerClass.getDeclaredMethod("post");
+
+		assertThatIllegalStateException()
+				.isThrownBy(() -> this.handlerMapping.getMappingForMethod(method, controllerClass))
+				.withMessageContainingAll(
+					method.toString(),
+					"is annotated with @RequestMapping and @HttpExchange annotations, but only one is allowed:",
+					"@" + PostMapping.class.getName(),
+					"@" + PostExchange.class.getName()
+				);
+	}
+
 	@SuppressWarnings("DataFlowIssue")
 	@Test
 	void httpExchangeWithDefaultValues() throws NoSuchMethodException {
@@ -364,6 +398,26 @@ class RequestMappingHandlerMappingTests {
 	}
 
 
+	@Controller
+	@RequestMapping("/api")
+	@HttpExchange("/api")
+	static class MixedClassLevelAnnotationsController {
+
+		@PostExchange("/post")
+		void post() {}
+	}
+
+
+	@Controller
+	@RequestMapping("/api")
+	static class MixedMethodLevelAnnotationsController {
+
+		@PostMapping("/post")
+		@PostExchange("/post")
+		void post() {}
+	}
+
+
 	@HttpExchange
 	@Target(ElementType.TYPE)
 	@Retention(RetentionPolicy.RUNTIME)

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerMapping.java

@@ -25,6 +25,7 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.function.Predicate;
+import java.util.stream.Stream;
 
 import jakarta.servlet.http.HttpServletRequest;
 
@@ -346,6 +347,7 @@ public class RequestMappingHandlerMapping extends RequestMappingInfoHandlerMappi
 
 	@Nullable
 	private RequestMappingInfo createRequestMappingInfo(AnnotatedElement element) {
+		RequestMappingInfo requestMappingInfo = null;
 		RequestCondition<?> customCondition = (element instanceof Class<?> clazz ?
 				getCustomTypeCondition(clazz) : getCustomMethodCondition((Method) element));
 
@@ -359,19 +361,22 @@ public class RequestMappingHandlerMapping extends RequestMappingInfoHandlerMappi
 				logger.warn("Multiple @RequestMapping annotations found on %s, but only the first will be used: %s"
 						.formatted(element, requestMappings));
 			}
-			return createRequestMappingInfo(requestMappings.get(0).annotation, customCondition);
+			requestMappingInfo = createRequestMappingInfo(requestMappings.get(0).annotation, customCondition);
 		}
 
 		List<AnnotationDescriptor<HttpExchange>> httpExchanges = getAnnotationDescriptors(
 				mergedAnnotations, HttpExchange.class);
 		if (!httpExchanges.isEmpty()) {
+			Assert.state(requestMappingInfo == null,
+					() -> "%s is annotated with @RequestMapping and @HttpExchange annotations, but only one is allowed: %s"
+							.formatted(element, Stream.of(requestMappings, httpExchanges).flatMap(List::stream).toList()));
 			Assert.state(httpExchanges.size() == 1,
 					() -> "Multiple @HttpExchange annotations found on %s, but only one is allowed: %s"
 							.formatted(element, httpExchanges));
-			return createRequestMappingInfo(httpExchanges.get(0).annotation, customCondition);
+			requestMappingInfo = createRequestMappingInfo(httpExchanges.get(0).annotation, customCondition);
 		}
 
-		return null;
+		return requestMappingInfo;
 	}
 
 	/**

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

@@ -310,6 +310,40 @@ class RequestMappingHandlerMappingTests {
 				);
 	}
 
+	@Test  // gh-32065
+	void httpExchangeWithMixedAnnotationsAtClassLevel() throws NoSuchMethodException {
+		RequestMappingHandlerMapping mapping = createMapping();
+
+		Class<?> controllerClass = MixedClassLevelAnnotationsController.class;
+		Method method = controllerClass.getDeclaredMethod("post");
+
+		assertThatIllegalStateException()
+				.isThrownBy(() -> mapping.getMappingForMethod(method, controllerClass))
+				.withMessageContainingAll(
+					controllerClass.getName(),
+					"is annotated with @RequestMapping and @HttpExchange annotations, but only one is allowed:",
+					"@" + RequestMapping.class.getName(),
+					"@" + HttpExchange.class.getName()
+				);
+	}
+
+	@Test  // gh-32065
+	void httpExchangeWithMixedAnnotationsAtMethodLevel() throws NoSuchMethodException {
+		RequestMappingHandlerMapping mapping = createMapping();
+
+		Class<?> controllerClass = MixedMethodLevelAnnotationsController.class;
+		Method method = controllerClass.getDeclaredMethod("post");
+
+		assertThatIllegalStateException()
+				.isThrownBy(() -> mapping.getMappingForMethod(method, controllerClass))
+				.withMessageContainingAll(
+					method.toString(),
+					"is annotated with @RequestMapping and @HttpExchange annotations, but only one is allowed:",
+					"@" + PostMapping.class.getName(),
+					"@" + PostExchange.class.getName()
+				);
+	}
+
 	@SuppressWarnings("DataFlowIssue")
 	@Test
 	void httpExchangeWithDefaultValues() throws NoSuchMethodException {
@@ -488,6 +522,26 @@ class RequestMappingHandlerMappingTests {
 	}
 
 
+	@Controller
+	@RequestMapping("/api")
+	@HttpExchange("/api")
+	static class MixedClassLevelAnnotationsController {
+
+		@PostExchange("/post")
+		void post() {}
+	}
+
+
+	@Controller
+	@RequestMapping("/api")
+	static class MixedMethodLevelAnnotationsController {
+
+		@PostMapping("/post")
+		@PostExchange("/post")
+		void post() {}
+	}
+
+
 	@HttpExchange
 	@Target(ElementType.TYPE)
 	@Retention(RetentionPolicy.RUNTIME)