Failing to deserialize packet id correct

[odd delta]

Hey, @verbal meteor!
Please remember to /close this post once your question has been answered!

[verbal meteor]

  public static List<IncomingPacket> deserialize(ByteBuf data, IncomingPacketRegistry incomingPacketRegistry)
            throws InstantiationException, IllegalAccessException {
        List<IncomingPacket> packets = new GlueList<>();

        for (ByteBuf packetBuf : splitPackets(data)) {
            int id = ByteBufUtil.readVarInt(packetBuf);

            System.out.println(id); // For some reason this is always zero.

            Class<? extends IncomingPacket> packetClass = incomingPacketRegistry.get(id);
            IncomingPacket packet = packetClass.newInstance();
            packet.deserialize(packetBuf);
            packets.add(packet);
        }

        data.discardReadBytes();
        return packets;
    }

    public static List<ByteBuf> splitPackets(ByteBuf buf) {
        List<ByteBuf> bufList = new GlueList<>();
        buf.markReaderIndex();
        byte[] lengthBytes = new byte[3];

        for (int position = 0; position < lengthBytes.length; ++position) {
            if (!buf.isReadable()) {
                buf.resetReaderIndex();
                return bufList;
            }

            lengthBytes[position] = buf.readByte();

            if (lengthBytes[position] < 0) {
                continue;
            }

            ByteBuf byteBuf = Unpooled.wrappedBuffer(lengthBytes);

            try {
                int length = ByteBufUtil.readVarInt(byteBuf);
                if (buf.readableBytes() < length) {
                    buf.resetReaderIndex();
                    return bufList;
                }
                bufList.add(buf.readBytes(length));
            } finally {
                byteBuf.release();
            }
            return bufList;
        }
        return bufList;
    }

The code that comes before it:

Method Inside Connection.java

    public void processPackets(ByteBuf buf) {

        List<IncomingPacket> receivedPackets;
        try {
            receivedPackets = PacketSerializer.deserialize(buf, INCOMING_PACKET_REGISTRY);

            for (IncomingPacket received : receivedPackets) {
                if (MinecraftServer.DEBUG_MESSAGES)
                    System.out.println("[Mineral] Packet received: " + received.getClass().getSimpleName());
                received.received(this);
            }
        } catch (InstantiationException | IllegalAccessException e) {
            e.printStackTrace();
        }
    }

Method inside ServerHandler.java (extends ChannelInboundHandlerAdapter)

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf in = (ByteBuf) msg;
        Connection connection = connected.getOrCreate(ctx);
        connection.processPackets(in);
    }