aging runtime. 
          The CallbackHandler instance must be initialized with any 
          application context needed to process the required callbacks 
          on behalf of the corresponding application.</dd>
<dt><span class="returnLabel">Returns:</span></dt>
<dd>A ClientAuthConfig Object that describes the configuration
                of ClientAuthModules at the message layer and messaging context
          identified by the layer and appContext arguments.
                This method does not retur