Polish "Stop closing parent's MeterRegistry beans when child context closes"

See gh-48319

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/MetricsAutoConfiguration.java

@@ -70,8 +70,8 @@ public class MetricsAutoConfiguration {
 	}
 
 	@Bean
-	MeterRegistryCloser meterRegistryCloser() {
-		return new MeterRegistryCloser();
+	MeterRegistryCloser meterRegistryCloser(ApplicationContext context) {
+		return new MeterRegistryCloser(context);
 	}
 
 	/**
@@ -80,12 +80,19 @@ public class MetricsAutoConfiguration {
 	 */
 	static class MeterRegistryCloser implements ApplicationListener<ContextClosedEvent> {
 
+		private final ApplicationContext context;
+
+		private final Iterable<MeterRegistry> meterRegistries;
+
+		MeterRegistryCloser(ApplicationContext context) {
+			this.meterRegistries = context.getBeansOfType(MeterRegistry.class).values();
+			this.context = context;
+		}
+
 		@Override
 		public void onApplicationEvent(ContextClosedEvent event) {
-			if (event.getApplicationContext().getParent() == null) {
-				for (MeterRegistry meterRegistry : event.getApplicationContext()
-					.getBeansOfType(MeterRegistry.class)
-					.values()) {
+			if (this.context.equals(event.getApplicationContext())) {
+				for (MeterRegistry meterRegistry : this.meterRegistries) {
 					if (!meterRegistry.isClosed()) {
 						meterRegistry.close();
 					}

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/MetricsAutoConfigurationTests.java

@@ -30,7 +30,6 @@ import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.core.annotation.Order;
 import org.springframework.test.util.ReflectionTestUtils;
 
@@ -92,17 +91,21 @@ class MetricsAutoConfigurationTests {
 	}
 
 	@Test
-	void meterRegistryCloserShouldNotCloseOnNonRootContextClosing() {
-		this.contextRunner.withUserConfiguration(MeterRegistryConfiguration.class).run((context) -> {
-			MeterRegistry meterRegistry = context.getBean(MeterRegistry.class);
-			GenericApplicationContext childContext = new GenericApplicationContext();
-			childContext.setParent(context);
-			childContext.refresh();
-			childContext.close();
-			assertThat(meterRegistry.isClosed()).isFalse();
-			context.close();
-			assertThat(meterRegistry.isClosed()).isTrue();
+	void meterRegistryCloserShouldOnlyCloseRegistriesBelongingToContextBeingClosed() {
+		MeterRegistry parentMeterRegistry = new SimpleMeterRegistry();
+		MeterRegistry childMeterRegistry = new SimpleMeterRegistry();
+		this.contextRunner.withBean(MeterRegistry.class, () -> parentMeterRegistry).run((parent) -> {
+			this.contextRunner.withBean(MeterRegistry.class, () -> childMeterRegistry)
+				.withParent(parent)
+				.run((child) -> {
+					assertThat(childMeterRegistry.isClosed()).isFalse();
+					assertThat(parentMeterRegistry.isClosed()).isFalse();
+				});
+			assertThat(childMeterRegistry.isClosed()).isTrue();
+			assertThat(parentMeterRegistry.isClosed()).isFalse();
 		});
+		assertThat(childMeterRegistry.isClosed()).isTrue();
+		assertThat(parentMeterRegistry.isClosed()).isTrue();
 	}
 
 	@Configuration(proxyBeanMethods = false)