code: private javax.jms.Message messageHandler(MessageManager messageManager) throws JMSException {
          if (messageManager == null) {
              return null;
          }        
          javax.jms.Message message = messageManager.getMessage();
          
          // Notify PrefetchThread that message is dispatched
          this.messageDispatched();
          acknowledger.notifyMessageReceived((SQSMessage) message);
          return message;
      }
docs: Helper that notifies PrefetchThread that message is dispatched and AutoAcknowledge