@Override
    public Collection<MUCOccupant> getOccupants(final JID user) {
        final List<MUCOccupant> userOccupants = new ArrayList<>();
        for (final MUCRoom room : localMUCRoomManager.getAll()) {
            final MUCOccupant occupant = room.getOccupantByFullJID(user);
            if (occupant != null) {
                userOccupants.add(occupant);
            }
        }
        return userOccupants;
    }
Removes a user from all chat rooms.

@param userAddress The user's normal jid, not the chat nickname jid.
xmppserver/src/main/java/org/jivesoftware/openfire/muc/spi/MultiUserChatServiceImpl.java