code: @Override
  	public void setMessageListener(MessageListener messageListener) throws JMSException
      {
      	externalAccessLock.readLock().lock();
      	try
  		{
      		checkNotClosed();
      		this.messageListener = messageListener;
  		}
      	finally
      	{
      		externalAccessLock.readLock().unlock();
      	}
      }
docs: /* (non-Javadoc)
  @see javax.jms.MessageConsumer#setMessageListener(javax.jms.MessageListener)