Merge branch '3.5.x'

Closes gh-48053

Author: mhalbritter

documentation/spring-boot-docs/src/docs/antora/modules/reference/pages/actuator/observability.adoc

@@ -29,6 +29,11 @@ Observability support relies on the https://github.com/micrometer-metrics/contex
 By default, javadoc:java.lang.ThreadLocal[] values are not automatically reinstated in reactive operators.
 This behavior is controlled with the configprop:spring.reactor.context-propagation[] property, which can be set to `auto` to enable automatic propagation.
 
+If you're working with javadoc:org.springframework.scheduling.annotation.Async[format=annotation] methods or use an javadoc:org.springframework.core.task.AsyncTaskExecutor[], you have to register the javadoc:org.springframework.core.task.support.ContextPropagatingTaskDecorator[] on the executor, otherwise the observability context is lost when switching threads.
+This can be done using this configuration:
+
+include-code::ContextPropagationConfiguration[]
+
 For more details about observations please see the {url-micrometer-docs}/observation[Micrometer Observation documentation].
 
 

documentation/spring-boot-docs/src/main/java/org/springframework/boot/docs/actuator/observability/contextpropagation/ContextPropagationConfiguration.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.docs.actuator.observability.contextpropagation;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.task.support.ContextPropagatingTaskDecorator;
+
+@Configuration(proxyBeanMethods = false)
+class ContextPropagationConfiguration {
+
+	@Bean
+	ContextPropagatingTaskDecorator contextPropagatingTaskDecorator() {
+		return new ContextPropagatingTaskDecorator();
+	}
+
+}

documentation/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/actuator/observability/contextpropagation/ContextPropagationConfiguration.kt

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.docs.actuator.observability.contextpropagation
+
+import org.springframework.context.annotation.Bean
+import org.springframework.context.annotation.Configuration
+import org.springframework.core.task.support.ContextPropagatingTaskDecorator
+
+@Configuration(proxyBeanMethods = false)
+class ContextPropagationConfiguration {
+
+	@Bean
+	fun contextPropagatingTaskDecorator(): ContextPropagatingTaskDecorator {
+		return ContextPropagatingTaskDecorator()
+	}
+
+}