INT-393: destroy() on DefaultMessageBus will automatically attempt to stop it, if that didn't happen already.

org.springframework.integration/src/main/java/org/springframework/integration/bus/DefaultMessageBus.java

@@ -331,6 +331,7 @@ public class DefaultMessageBus implements MessageBus, ApplicationContextAware, A
 	}
 
 	public void destroy() throws Exception {
+		this.stop();
 		if (this.taskScheduler instanceof DisposableBean) {
 			((DisposableBean) this.taskScheduler).destroy();
 		}