#vulnerable code 
                                public void disconnect() {
        ChannelFuture future = send(new Packet(PacketType.DISCONNECT));
        future.addListener(ChannelFutureListener.CLOSE);

        onChannelDisconnect();
    } 
                            #location 3 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public void disconnect() {
        ChannelFuture future = send(new Packet(PacketType.DISCONNECT));
		if(future != null) {
			future.addListener(ChannelFutureListener.CLOSE);
		}

        onChannelDisconnect();
    }