byte opcode[] = { datagram[header_size-2], datagram[header_size-1] };
byte opcode[] = { datagram[header_size-1], datagram[header_size-2] };
    public static short getOpcode(byte [] datagram)    {	byte opcode[] = { datagram[header_size-2], datagram[header_size-1] };	ByteBuffer bb = ByteBuffer.wrap(opcode);	return bb.getShort();    }