code> class
 is already present among the previously registered component classes or instances
 in the configuration context.
 </p></div>
<dl>
<dt><span class="paramLabel">Parameters:</span></dt>
<dd><code>componentClass</code> - a component class to test for.</dd>
<dt><span class="returnLabel">Returns:</span></dt>
<dd><code>true</code> if a component of a given class has been previously registered in this
         configuration context, <code>false</code> otherwise.</dd>
<dt><span class="seeLabel">See Also