Honour EndpointFilter configured on an endpoint's superclass

Previously, @EndpointFilter would only have an effect when used as
an annotation or meta-annotation on the endpoint class itself. It
would have no effect when used on a super-class of the endpoint
bean's class.

This commit updates EndpointDiscoverer so that an @EndpointFilter
annotation or meta-annotation on a super-class will be found and
applied to the discovery process. This is achieved by using find…
rather than get… when retrieving the attributes for the EndpointFilter
annotation.

Fixes gh-17866

Author: wilkinsona

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/annotation/EndpointDiscoverer.java

@@ -423,8 +423,8 @@ public Set<ExtensionBean> getExtensions() {
 		}
 
 		private Class<?> getFilter(Class<?> type) {
-			AnnotationAttributes attributes = AnnotatedElementUtils.getMergedAnnotationAttributes(type,
-					FilteredEndpoint.class);
+			AnnotationAttributes attributes = AnnotatedElementUtils.findMergedAnnotationAttributes(type,
+					FilteredEndpoint.class, false, true);
 			if (attributes == null) {
 				return null;
 			}

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/annotation/EndpointDiscovererTests.java

@@ -209,7 +209,8 @@ public void getEndpointsWhenHasSpecializedFiltersInSpecializedDiscovererShouldNo
 		load(SpecializedEndpointsConfiguration.class, (context) -> {
 			SpecializedEndpointDiscoverer discoverer = new SpecializedEndpointDiscoverer(context);
 			Map<EndpointId, SpecializedExposableEndpoint> endpoints = mapEndpoints(discoverer.getEndpoints());
-			assertThat(endpoints).containsOnlyKeys(EndpointId.of("test"), EndpointId.of("specialized"));
+			assertThat(endpoints).containsOnlyKeys(EndpointId.of("test"), EndpointId.of("specialized"),
+					EndpointId.of("specialized-superclass"));
 		});
 	}
 
@@ -252,7 +253,7 @@ public void getEndpointsShouldApplyFilters() {
 		load(SpecializedEndpointsConfiguration.class, (context) -> {
 			EndpointFilter<SpecializedExposableEndpoint> filter = (endpoint) -> {
 				EndpointId id = endpoint.getEndpointId();
-				return !id.equals(EndpointId.of("specialized"));
+				return !id.equals(EndpointId.of("specialized")) && !id.equals(EndpointId.of("specialized-superclass"));
 			};
 			SpecializedEndpointDiscoverer discoverer = new SpecializedEndpointDiscoverer(context,
 					Collections.singleton(filter));
@@ -401,7 +402,8 @@ public TestEndpoint scopedTargetTestEndpoint() {
 
 	}
 
-	@Import({ TestEndpoint.class, SpecializedTestEndpoint.class, SpecializedExtension.class })
+	@Import({ TestEndpoint.class, SpecializedTestEndpoint.class, SpecializedSuperclassTestEndpoint.class,
+			SpecializedExtension.class })
 	static class SpecializedEndpointsConfiguration {
 
 	}
@@ -494,6 +496,20 @@ public Object getAll() {
 
 	}
 
+	@SpecializedEndpoint(id = "specialized-superclass")
+	static class AbstractFilteredEndpoint {
+
+	}
+
+	static class SpecializedSuperclassTestEndpoint extends AbstractFilteredEndpoint {
+
+		@ReadOperation
+		public Object getAll() {
+			return null;
+		}
+
+	}
+
 	static class SubSpecializedTestEndpoint extends SpecializedTestEndpoint {
 
 		@ReadOperation