GH-3371: Fence child containers after ConcurrentContainer stops

Fixes: #3371

Containers are not restricted from starting after ConcurrentContainer stopped or restarted. These changes would fix this issue.

* Enhancements to fence container after ConcurrentContainer stops

(cherry picked from commit 20696f2)

# Conflicts:
#	spring-kafka/src/main/java/org/springframework/kafka/listener/AbstractMessageListenerContainer.java

spring-kafka/src/main/java/org/springframework/kafka/listener/AbstractMessageListenerContainer.java

@@ -123,6 +123,8 @@ public abstract class AbstractMessageListenerContainer<K, V>
 
 	private volatile boolean running = false;
 
+	private volatile boolean fenced = false;
+
 	private volatile boolean paused;
 
 	private volatile boolean stoppedNormally = true;
@@ -274,6 +276,10 @@ public boolean isRunning() {
 		return this.running;
 	}
 
+	protected void setFenced(boolean fenced) {
+		this.fenced = fenced;
+	}
+
 	protected boolean isPaused() {
 		return this.paused;
 	}
@@ -507,6 +513,7 @@ public final void start() {
 			if (!isRunning()) {
 				Assert.state(this.containerProperties.getMessageListener() instanceof GenericMessageListener,
 						() -> "A " + GenericMessageListener.class.getName() + " implementation must be provided");
+				Assert.state(!this.fenced, "Container Fenced. It is not allowed to start.");
 				doStart();
 			}
 		}

spring-kafka/src/main/java/org/springframework/kafka/listener/ConcurrentMessageListenerContainer.java

@@ -351,6 +351,7 @@ protected void doStop(final Runnable callback, boolean normal) {
 				}
 			}
 			for (KafkaMessageListenerContainer<K, V> container : this.containers) {
+				container.setFenced(true);
 				if (container.isRunning()) {
 					if (normal) {
 						container.stop(() -> {

spring-kafka/src/test/java/org/springframework/kafka/listener/ConcurrentMessageListenerContainerTests.java

@@ -17,6 +17,7 @@
 package org.springframework.kafka.listener;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.BDDMockito.given;
@@ -198,6 +199,7 @@ protected Consumer<Integer, String> createKafkaConsumer(String groupId, String c
 		assertThat(container.metrics()).isNotNull();
 		Set<KafkaMessageListenerContainer<Integer, String>> children = new HashSet<>(containers);
 		assertThat(container.isInExpectedState()).isTrue();
+		MessageListenerContainer childContainer = container.getContainers().get(0);
 		container.getContainers().get(0).stopAbnormally(() -> { });
 		assertThat(container.isInExpectedState()).isFalse();
 		container.getContainers().get(0).start();
@@ -220,6 +222,10 @@ protected Consumer<Integer, String> createKafkaConsumer(String groupId, String c
 		});
 		assertThat(overrides.get().getProperty(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG)).isNull();
 		this.logger.info("Stop auto");
+		assertThat(childContainer.isRunning()).isFalse();
+		assertThat(container.isRunning()).isFalse();
+		// Fenced container. Throws exception
+		assertThatExceptionOfType(IllegalStateException.class).isThrownBy(() -> childContainer.start());
 	}
 
 	@Test