SimpAnnotationMethodMessageHandler ignores empty marker annotations

Issue: SPR-13704

Author: jhoeller

spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandler.java

@@ -81,6 +81,7 @@
  *
  * @author Rossen Stoyanchev
  * @author Brian Clozel
+ * @author Juergen Hoeller
  * @since 4.0
  */
 public class SimpAnnotationMethodMessageHandler extends AbstractMethodMessageHandler<SimpMessageMappingInfo>
@@ -364,36 +365,47 @@ protected boolean isHandler(Class<?> beanType) {
 
 	@Override
 	protected SimpMessageMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {
-		MessageMapping typeAnnotation = AnnotationUtils.findAnnotation(handlerType, MessageMapping.class);
-		MessageMapping messageAnnotation = AnnotationUtils.findAnnotation(method, MessageMapping.class);
-		if (messageAnnotation != null) {
-			SimpMessageMappingInfo result = createMessageMappingCondition(messageAnnotation);
-			if (typeAnnotation != null) {
-				result = createMessageMappingCondition(typeAnnotation).combine(result);
+		MessageMapping messageAnn = AnnotationUtils.findAnnotation(method, MessageMapping.class);
+		if (messageAnn != null) {
+			MessageMapping typeAnn = AnnotationUtils.findAnnotation(handlerType, MessageMapping.class);
+			// Only actually register it if there are destinations specified;
+			// otherwise @MessageMapping is just being used as a (meta-annotation) marker.
+			if (messageAnn.value().length > 0 || (typeAnn != null && typeAnn.value().length > 0)) {
+				SimpMessageMappingInfo result = createMessageMappingCondition(messageAnn.value());
+				if (typeAnn != null) {
+					result = createMessageMappingCondition(typeAnn.value()).combine(result);
+				}
+				return result;
 			}
-			return result;
 		}
-		SubscribeMapping subscribeAnnotation = AnnotationUtils.findAnnotation(method, SubscribeMapping.class);
-		if (subscribeAnnotation != null) {
-			SimpMessageMappingInfo result = createSubscribeCondition(subscribeAnnotation);
-			if (typeAnnotation != null) {
-				result = createMessageMappingCondition(typeAnnotation).combine(result);
+
+		SubscribeMapping subscribeAnn = AnnotationUtils.findAnnotation(method, SubscribeMapping.class);
+		if (subscribeAnn != null) {
+			MessageMapping typeAnn = AnnotationUtils.findAnnotation(handlerType, MessageMapping.class);
+			// Only actually register it if there are destinations specified;
+			// otherwise @SubscribeMapping is just being used as a (meta-annotation) marker.
+			if (subscribeAnn.value().length > 0 || (typeAnn != null && typeAnn.value().length > 0)) {
+				SimpMessageMappingInfo result = createSubscribeMappingCondition(subscribeAnn.value());
+				if (typeAnn != null) {
+					result = createMessageMappingCondition(typeAnn.value()).combine(result);
+				}
+				return result;
 			}
-			return result;
 		}
+
 		return null;
 	}
 
-	private SimpMessageMappingInfo createMessageMappingCondition(MessageMapping annotation) {
-		String[] destinations = resolveEmbeddedValuesInDestinations(annotation.value());
+	private SimpMessageMappingInfo createMessageMappingCondition(String[] destinations) {
+		String[] resolvedDestinations = resolveEmbeddedValuesInDestinations(destinations);
 		return new SimpMessageMappingInfo(SimpMessageTypeMessageCondition.MESSAGE,
-				new DestinationPatternsMessageCondition(destinations, this.pathMatcher));
+				new DestinationPatternsMessageCondition(resolvedDestinations, this.pathMatcher));
 	}
 
-	private SimpMessageMappingInfo createSubscribeCondition(SubscribeMapping annotation) {
-		String[] destinations = resolveEmbeddedValuesInDestinations(annotation.value());
+	private SimpMessageMappingInfo createSubscribeMappingCondition(String[] destinations) {
+		String[] resolvedDestinations = resolveEmbeddedValuesInDestinations(destinations);
 		return new SimpMessageMappingInfo(SimpMessageTypeMessageCondition.SUBSCRIBE,
-				new DestinationPatternsMessageCondition(destinations, this.pathMatcher));
+				new DestinationPatternsMessageCondition(resolvedDestinations, this.pathMatcher));
 	}
 
 	/**