Javadoc
The user subscribes to the node using the supplied jid. The
bare jid portion of this one must match the jid for the connection.
Please note that the
Subscription.State should be checked
on return since more actions may be required by the caller.
Subscription.State#pending - The owner must approve the subscription
request before messages will be received.
Subscription.State#unconfigured - If the
Subscription#isConfigRequired() is true,
the caller must configure the subscription before messages will be received. If it is false
the caller can configure it but is not required to do so.