public void userBroadcast(String username, Packet packet) throws PacketException {
        // TODO broadcast to ALL sessions of the user and not only available
        for (JID address : routingTable.getRoutes(new JID(username, serverName, null), null)) {
            packet.setTo(address);
            routingTable.routePacket(address, packet);
        }
    }
Broadcasts the given data to all connected sessions for a particular
user. Excellent for updating all connected resources for users such as
roster pushes.

@param username the user to send the boradcast to.
@param packet the packet to be broadcast.
@throws PacketException if a packet exception occurs.
xmppserver/src/main/java/org/jivesoftware/openfire/SessionManager.java