Polish "Add auto-configuration for ObservedAspect"

See gh-35191

Author: snicoll

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/observation/ObservationAutoConfigurationTests.java

@@ -180,6 +180,14 @@ void allowsObservedAspectToBeDisabled() {
 			.run((context) -> assertThat(context).doesNotHaveBean(ObservedAspect.class));
 	}
 
+	@Test
+	void allowsObservedAspectToBeCustomized() {
+		this.contextRunner.withUserConfiguration(CustomObservedAspectConfiguration.class)
+			.run((context) -> assertThat(context).hasSingleBean(ObservedAspect.class)
+				.getBean(ObservedAspect.class)
+				.isSameAs(context.getBean("customObservedAspect")));
+	}
+
 	@Test
 	void autoConfiguresObservationPredicates() {
 		this.contextRunner.withUserConfiguration(ObservationPredicates.class).run((context) -> {
@@ -353,6 +361,16 @@ ObservationFilter observationFilterTwo() {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class CustomObservedAspectConfiguration {
+
+		@Bean
+		ObservedAspect customObservedAspect(ObservationRegistry observationRegistry) {
+			return new ObservedAspect(observationRegistry);
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class CustomGlobalObservationConvention {