Add an option to leave group when closing streams

Fixes: spring-projects#3168 

* Adding an option in `StreamsBuilderFactoryBean` to allow the consumer
   to leave the group upon closing the Kafka Streams.

Author: juwit

spring-kafka-docs/src/main/antora/modules/ROOT/pages/streams.adoc

@@ -213,6 +213,14 @@ You can declare and use any additional `StreamsBuilderFactoryBean` beans as well
 You can perform additional customization of that bean, by providing a bean that implements `StreamsBuilderFactoryBeanConfigurer`.
 If there are multiple such beans, they will be applied according to their `Ordered.order` property.
 
+
+=== Cleanup & Stop configuration
+
+When the factory is stopped, the `KafkaStreams.close()` is called with 2 parameters :
+
+* closeTimeout : how long to to wait for the threads to shutdown (defaults to `DEFAULT_CLOSE_TIMEOUT` set to 10 seconds). Can be configured using `StreamsBuilderFactoryBean.setCloseTimeout()`.
+* leaveGroupOnClose : to trigger consumer leave call from the group (defaults to `false`). Can be configured using `StreamsBuilderFactoryBean.setLeaveGroupOnClose()`.
+
 By default, when the factory bean is stopped, the `KafkaStreams.cleanUp()` method is called.
 Starting with version 2.1.2, the factory bean has additional constructors, taking a `CleanupConfig` object that has properties to let you control whether the `cleanUp()` method is called during `start()` or `stop()` or neither.
 Starting with version 2.7, the default is to never clean up local state.

spring-kafka/src/main/java/org/springframework/kafka/config/StreamsBuilderFactoryBean.java

@@ -55,6 +55,7 @@
  * @author Nurettin Yilmaz
  * @author Denis Washington
  * @author Gary Russell
+ * @author Julien Wittouck
  *
  * @since 1.1.4
  */
@@ -100,6 +101,8 @@ public class StreamsBuilderFactoryBean extends AbstractFactoryBean<StreamsBuilde
 
 	private Duration closeTimeout = DEFAULT_CLOSE_TIMEOUT;
 
+	private boolean leaveGroupOnClose = false;
+
 	private KafkaStreams kafkaStreams;
 
 	private volatile boolean running;
@@ -225,6 +228,15 @@ public void setCloseTimeout(int closeTimeout) {
 		this.closeTimeout = Duration.ofSeconds(closeTimeout); // NOSONAR (sync)
 	}
 
+	/**
+	 * Specify if the consumer should leave the group when stopping Kafka Streams. Defaults to false.
+	 * @param leaveGroupOnClose true to leave the group when stopping the Streams
+	 * @since 3.2.0
+	 */
+	public void setLeaveGroupOnClose(boolean leaveGroupOnClose) {
+		this.leaveGroupOnClose = leaveGroupOnClose;
+	}
+
 	/**
 	 * Providing access to the associated {@link Topology} of this
 	 * {@link StreamsBuilderFactoryBean}.
@@ -383,7 +395,10 @@ public void stop() {
 			if (this.running) {
 				try {
 					if (this.kafkaStreams != null) {
-						this.kafkaStreams.close(this.closeTimeout);
+						this.kafkaStreams.close(new KafkaStreams.CloseOptions()
+								.timeout(this.closeTimeout)
+								.leaveGroup(this.leaveGroupOnClose)
+						);
 						if (this.cleanupConfig.cleanupOnStop()) {
 							this.kafkaStreams.cleanUp();
 						}