@Override
    public void deliver(@Nonnull final Packet packet) throws UnauthorizedException, PacketException {
        if (packet == null) {
            throw new PacketException("Packet was null");
        }
        if (deliverHandler == null) {
            throw new PacketException("Could not send packet - no route: " + packet.toString());
        }
        // Let the SocketPacketWriteHandler process the packet. SocketPacketWriteHandler may send
        // it over the socket or store it when user is offline or drop it.
        deliverHandler.process(packet);
    }
The handler that does the actual delivery (could be a channel instead)
xmppserver/src/main/java/org/jivesoftware/openfire/spi/PacketDelivererImpl.java