he state of these message header fields and properties is undefined.

 <p>
 <b>Restrictions on threading</b>: Applications that perform an asynchronous send must confirm to the threading
 restrictions defined in JMS. This means that the session may be used by only one thread at a time.

 <p>
 Setting a <tt>CompletionListener</tt> does not cause the session to be dedicated to the thread of control which calls
 the <tt>CompletionListener</tt>. The application thread may therefore continue to use the session a