e message object for a message exchange. This
 interface may also be used to associate additional context in the form of key/value pairs, with the encapsulated
 messages.
 <p>
 Every implementation of this interface should provide a zero argument constructor, and a constructor which takes a
 single Map argument. Additional constructors may also be provided.</div>
<dl>
<dt><span class="seeLabel">See Also:</span></dt>
<dd><a href="https://docs.oracle.com/javase/8/docs/api/java/util/Map.html?is-external=true" 