public Collection<JID> getContacts() {
        return Collections.unmodifiableCollection(contacts);
    }
Returns the JIDs of those to contact with questions. This information is not used by
the pubsub service. It is meant to be "discovered" by users and redirect any question
to the returned people to contact.

@return the JIDs of those to contact with questions.
xmppserver/src/main/java/org/jivesoftware/openfire/pubsub/Node.java