@Override
    public int getMaxStages(@Nonnull final SessionData data) {
        return 0;
    }
Command that allows to retrieve the number of online users who are active at any one moment.
Active users are those users that have sent an available presence.

@author Gaston Dombiak
@see <a href="https://xmpp.org/extensions/xep-0133.html#get-active-users-num">XEP-0133 Service Administration: Get Number of Active Users</a>
xmppserver/src/main/java/org/jivesoftware/openfire/commands/admin/GetNumberActiveUsers.java