an the queue's messages.
 It may be an enumeration of the entire content of a queue, or it may contain only the messages matching a message
 selector.

 <p>
 Messages may be arriving and expiring while the scan is done. The Jakarta Messaging API does not require the content of an
 enumeration to be a static snapshot of queue content. Whether these changes are visible or not depends on the JMS
 provider.
 <p>
 A message must not be returned by a <code>QueueBrowser</code> before its delivery time has been rea