* @throws rocks.xmpp.core.stanza.model.StanzaException If the entity returned a stanza error.
* @throws rocks.xmpp.core.session.NoResponseException If the entity did not respond.
* @see <a href="http://xmpp.org/extensions/xep-0060.html#subscriber-configure-submit">6.4 Request Default Subscription Configuration Options</a>
*/
private DataForm getDefaultSubscriptionOptions() throws XmppException {
IQ result = xmppSession.query(new IQ(service, IQ.Type.GET, PubSub.withDefault()));
PubSub pubSub = result.getExtension(PubSub.class);
return pubSub.getDefault().getDataForm();
}