Fix extension discovery when endpoint instance is sub-classed

This commit fixes endpoint extension discovery when the related endpoint
is sub-classed. Previously, a strict by type check was applied against
the `endpoint` attribute of `EndpointExtension`.

Rather than using a `Class` check, this commit extracts the id of an
endpoint and uses it to match its extension, if any.

Closes gh-13082

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

@@ -145,17 +145,17 @@ public abstract class EndpointDiscoverer<E extends ExposableEndpoint<O>, O exten
 	}
 
 	private void addExtensionBeans(Collection<EndpointBean> endpointBeans) {
-		Map<?, EndpointBean> byType = endpointBeans.stream()
-				.collect(Collectors.toMap((bean) -> bean.getType(), (bean) -> bean));
+		Map<String, EndpointBean> byId = endpointBeans.stream()
+				.collect(Collectors.toMap(EndpointBean::getId, (bean) -> bean));
 		String[] beanNames = BeanFactoryUtils.beanNamesForAnnotationIncludingAncestors(
 				this.applicationContext, EndpointExtension.class);
 		for (String beanName : beanNames) {
 			ExtensionBean extensionBean = createExtensionBean(beanName);
-			EndpointBean endpointBean = byType.get(extensionBean.getEndpointType());
+			EndpointBean endpointBean = byId.get(extensionBean.getEndpointId());
 			Assert.state(endpointBean != null,
 					() -> ("Invalid extension '" + extensionBean.getBeanName()
-							+ "': no endpoint found with type '"
-							+ extensionBean.getEndpointType().getName() + "'"));
+							+ "': no endpoint found with id '"
+							+ extensionBean.getEndpointId() + "'"));
 			addExtensionBean(endpointBean, extensionBean);
 		}
 	}
@@ -488,20 +488,24 @@ public abstract class EndpointDiscoverer<E extends ExposableEndpoint<O>, O exten
 
 		private final Object bean;
 
-		private final Class<?> endpointType;
+		private final String endpointId;
 
 		private final Class<?> filter;
 
 		ExtensionBean(String beanName, Object bean) {
+			this.bean = bean;
+			this.beanName = beanName;
 			AnnotationAttributes attributes = AnnotatedElementUtils
 					.getMergedAnnotationAttributes(bean.getClass(),
 							EndpointExtension.class);
-			this.beanName = beanName;
-			this.bean = bean;
-			this.endpointType = attributes.getClass("endpoint");
+			Class<?> endpointType = attributes.getClass("endpoint");
+			AnnotationAttributes endpointAttributes = AnnotatedElementUtils
+					.findMergedAnnotationAttributes(endpointType, Endpoint.class, true,
+							true);
+			Assert.state(endpointAttributes != null, () -> "Extension "
+					+ endpointType.getName() + " does not specify an endpoint");
+			this.endpointId = endpointAttributes.getString("id");
 			this.filter = attributes.getClass("filter");
-			Assert.state(!this.endpointType.equals(Void.class), () -> "Extension "
-					+ this.endpointType.getName() + " does not specify an endpoint");
 		}
 
 		public String getBeanName() {
@@ -512,8 +516,8 @@ public abstract class EndpointDiscoverer<E extends ExposableEndpoint<O>, O exten
 			return this.bean;
 		}
 
-		public Class<?> getEndpointType() {
-			return this.endpointType;
+		public String getEndpointId() {
+			return this.endpointId;
 		}
 
 		public Class<?> getFilter() {

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

@@ -233,6 +233,25 @@ public class EndpointDiscovererTests {
 		});
 	}
 
+	@Test
+	public void getEndpointShouldFindParentExtension() {
+		load(SubSpecializedEndpointsConfiguration.class, (context) -> {
+			SpecializedEndpointDiscoverer discoverer = new SpecializedEndpointDiscoverer(
+					context);
+			Map<String, SpecializedExposableEndpoint> endpoints = mapEndpoints(
+					discoverer.getEndpoints());
+			Map<Method, SpecializedOperation> operations = mapOperations(
+					endpoints.get("specialized"));
+			assertThat(operations).containsKeys(
+					ReflectionUtils.findMethod(SpecializedTestEndpoint.class, "getAll"));
+			assertThat(operations).containsKeys(ReflectionUtils.findMethod(
+					SubSpecializedTestEndpoint.class, "getSpecialOne", String.class));
+			assertThat(operations).containsKeys(
+					ReflectionUtils.findMethod(SpecializedExtension.class, "getSpecial"));
+			assertThat(operations).hasSize(3);
+		});
+	}
+
 	@Test
 	public void getEndpointsShouldApplyFilters() {
 		load(SpecializedEndpointsConfiguration.class, (context) -> {
@@ -371,6 +390,12 @@ public class EndpointDiscovererTests {
 
 	}
 
+	@Import({ TestEndpoint.class, SubSpecializedTestEndpoint.class,
+			SpecializedExtension.class })
+	static class SubSpecializedEndpointsConfiguration {
+
+	}
+
 	@Endpoint(id = "test")
 	static class TestEndpoint {
 
@@ -449,6 +474,15 @@ public class EndpointDiscovererTests {
 
 	}
 
+	static class SubSpecializedTestEndpoint extends SpecializedTestEndpoint {
+
+		@ReadOperation
+		public Object getSpecialOne(@Selector String id) {
+			return null;
+		}
+
+	}
+
 	static class TestEndpointDiscoverer
 			extends EndpointDiscoverer<TestExposableEndpoint, TestOperation> {
 

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

@@ -117,8 +117,7 @@ public class JmxEndpointDiscovererTests {
 			this.thrown.expect(IllegalStateException.class);
 			this.thrown.expectMessage(
 					"Invalid extension 'jmxEndpointDiscovererTests.TestJmxEndpointExtension': "
-							+ "no endpoint found with type '"
-							+ TestEndpoint.class.getName() + "'");
+							+ "no endpoint found with id 'test'");
 			discoverer.getEndpoints();
 		});
 	}

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

@@ -82,8 +82,8 @@ public class WebEndpointDiscovererTests {
 		load(TestWebEndpointExtensionConfiguration.class, (discoverer) -> {
 			this.thrown.expect(IllegalStateException.class);
 			this.thrown.expectMessage(
-					"Invalid extension 'endpointExtension': no endpoint found with type '"
-							+ TestEndpoint.class.getName() + "'");
+					"Invalid extension 'endpointExtension': no endpoint found with id '"
+							+ "test'");
 			discoverer.getEndpoints();
 		});
 	}