Expose JMS message listener container ids

Issue: SPR-13633

spring-jms/src/main/java/org/springframework/jms/config/JmsListenerEndpointRegistry.java

@@ -19,6 +19,7 @@ package org.springframework.jms.config;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicInteger;
 
@@ -68,12 +69,21 @@ public class JmsListenerEndpointRegistry implements DisposableBean, SmartLifecyc
 	 * @param id the id of the container
 	 * @return the container or {@code null} if no container with that id exists
 	 * @see JmsListenerEndpoint#getId()
+	 * @see #getListenerContainerIds()
 	 */
 	public MessageListenerContainer getListenerContainer(String id) {
 		Assert.notNull(id, "Container identifier must not be null");
 		return this.listenerContainers.get(id);
 	}
 
+	/**
+	 * Return the ids of the managed {@link MessageListenerContainer} instance(s).
+	 * @see #getListenerContainer(String)
+	 */
+	public Set<String> getListenerContainerIds() {
+		return Collections.unmodifiableSet(this.listenerContainers.keySet());
+	}
+
 	/**
 	 * Return the managed {@link MessageListenerContainer} instance(s).
 	 */