How to use the bytebuffer.concat function in bytebuffer

process.stdin.on('readable', () => {
    const chunk = process.stdin.read();
    if (!chunk) return;

    const wrapped = ByteBuffer.wrap(chunk);
    buf = buf ? ByteBuffer.concat([buf, wrapped]) : wrapped;
    try {
      let req: WorkRequest;
      // Read all requests that have accumulated in the buffer.
      while ((req = workerpb.WorkRequest.decodeDelimited(buf)) != null) {
        debug('=== Handling new build request');
        // Reset accumulated log output.
        consoleOutput = '';
        const args = req.getArguments();
        const inputs: {[path: string]: string} = {};
        for (const input of req.getInputs()) {
          inputs[input.getPath()] = input.getDigest().toString('hex');
        }
        debug('Compiling with:\n\t' + args.join('\n\t'));
        const exitCode = runOneBuild(args, inputs) ? 0 : 1;
        process.stdout.write(new workerpb.WorkResponse()
                                 .setExitCode(exitCode)

}

        if([1, 3, 4, 7].includes(packet.reliability)) {
          byteBuffer.flip()
          byteBuffer = ByteBuffer.concat([byteBuffer, EncapsulatedPacket.writeLTriad(packet.orderIndex)])
          byteBuffer.offset = byteBuffer.limit
          byteBuffer.writeByte(packet.orderChannel)
        }

        if(packet.hasSplit) {
          byteBuffer.writeInt(packet.splitCount)
          byteBuffer.writeShort(packet.splitId)
          byteBuffer.writeInt(packet.splitIndex)
        }

        byteBuffer = ByteBuffer.concat([byteBuffer.reset(), packetBuffer])
        byteBuffer.offset = byteBuffer.limit
      })
    }

if(!packet.hasSplit) packet.hasSplit = false

        const packetBuffer = packet.encode()

        byteBuffer.writeByte((packet.reliability << 5) | (packet.hasSplit ? 0x10 : 0x00))
        byteBuffer.writeShort(packetBuffer.limit << 3)

        if([2, 3, 4, 6, 7].includes(packet.reliability)) {
          byteBuffer.flip()
          byteBuffer = ByteBuffer.concat([byteBuffer, EncapsulatedPacket.writeLTriad(packet.messageIndex)])
          byteBuffer.offset = byteBuffer.limit
        }

        if([1, 3, 4, 7].includes(packet.reliability)) {
          byteBuffer.flip()
          byteBuffer = ByteBuffer.concat([byteBuffer, EncapsulatedPacket.writeLTriad(packet.orderIndex)])
          byteBuffer.offset = byteBuffer.limit
          byteBuffer.writeByte(packet.orderChannel)
        }

        if(packet.hasSplit) {
          byteBuffer.writeInt(packet.splitCount)
          byteBuffer.writeShort(packet.splitId)
          byteBuffer.writeInt(packet.splitIndex)
        }

        byteBuffer = ByteBuffer.concat([byteBuffer.reset(), packetBuffer])
        byteBuffer.offset = byteBuffer.limit
      })
    }

this.packets.forEach(packet => {
        if(!packet.reliability) packet.reliability = 0
        if(!packet.hasSplit) packet.hasSplit = false

        const packetBuffer = packet.encode()

        byteBuffer.writeByte((packet.reliability << 5) | (packet.hasSplit ? 0x10 : 0x00))
        byteBuffer.writeShort(packetBuffer.limit << 3)

        if([2, 3, 4, 6, 7].includes(packet.reliability)) {
          byteBuffer.flip()
          byteBuffer = ByteBuffer.concat([byteBuffer, EncapsulatedPacket.writeLTriad(packet.messageIndex)])
          byteBuffer.offset = byteBuffer.limit
        }

        if([1, 3, 4, 7].includes(packet.reliability)) {
          byteBuffer.flip()
          byteBuffer = ByteBuffer.concat([byteBuffer, EncapsulatedPacket.writeLTriad(packet.orderIndex)])
          byteBuffer.offset = byteBuffer.limit
          byteBuffer.writeByte(packet.orderChannel)
        }

        if(packet.hasSplit) {
          byteBuffer.writeInt(packet.splitCount)
          byteBuffer.writeShort(packet.splitId)
          byteBuffer.writeInt(packet.splitIndex)
        }

encode() {
    let byteBuffer = new ByteBuffer()

    if(this.packets.length) {
      byteBuffer.writeByte(this.id)
      byteBuffer.flip()
      byteBuffer = ByteBuffer.concat([byteBuffer, EncapsulatedPacket.writeLTriad(this.sequenceNumber)])
      byteBuffer.offset = byteBuffer.limit

      this.packets.forEach(packet => {
        if(!packet.reliability) packet.reliability = 0
        if(!packet.hasSplit) packet.hasSplit = false

        const packetBuffer = packet.encode()

        byteBuffer.writeByte((packet.reliability << 5) | (packet.hasSplit ? 0x10 : 0x00))
        byteBuffer.writeShort(packetBuffer.limit << 3)

        if([2, 3, 4, 6, 7].includes(packet.reliability)) {
          byteBuffer.flip()
          byteBuffer = ByteBuffer.concat([byteBuffer, EncapsulatedPacket.writeLTriad(packet.messageIndex)])
          byteBuffer.offset = byteBuffer.limit
        }