write the descriptor class to a DOM tree and return it
if (! (descriptor instanceof MessageListener)) {
throw new IllegalArgumentException(getClass() + " cannot handle descriptors of type " + descriptor.getClass());
}
MessageListener msgListener = (MessageListener)descriptor;
Node actSpecNode = appendChild(parent, ConnectorTagNames.ACTIVATION_SPEC);
appendTextChild(actSpecNode, ConnectorTagNames.ACTIVATION_SPEC_CLASS, msgListener.getActivationSpecClass());
//required-config-property
RequiredConfigNode reqNode = new RequiredConfigNode();
actSpecNode = reqNode.writeDescriptor(actSpecNode, msgListener);
return parent;