public void removeOccupant(@Nonnull final MUCOccupant occupant) {
        Log.trace( "Remove occupant from room {}: {}", this.getJID(), occupant );
        occupants.remove(occupant);
        MUCEventDispatcher.occupantLeft(occupant.getOccupantJID(), occupant.getUserAddress(), occupant.getNickname());
    }
Removes the occupant from all the internal occupants collections. The occupant data will
also be removed from the user's occupant-data collection.

@param occupant the occupant to remove.
xmppserver/src/main/java/org/jivesoftware/openfire/muc/MUCRoom.java