SPRNET-1089 - Change DoStop() in AbstractListenerContainer to protected

src/Spring/Spring.Messaging/Messaging/Listener/AbstractPeekingMessageListenerContainer.cs

@@ -164,7 +164,7 @@ namespace Spring.Messaging.Listener
         /// <summary>
         /// Stops peeking on the message queue.
         /// </summary>
-        public override void DoStop()
+        protected override void DoStop()
         {
             base.DoStop();
             stopEvent.Set();