public void setPersistent(boolean persistent) {
        this.persistent = persistent;
    }
Sets if the room is not destroyed if the last occupant exits. Persistent rooms are
saved to the database to make their configurations persistent together with the affiliation
of the users.

@param persistent if the room is not destroyed if the last occupant exits.
xmppserver/src/main/java/org/jivesoftware/openfire/muc/MUCRoom.java