// Set a new payload and verify
        byte[] payload1 = "test_payload_1".getBytes();
        message.setRawPayload(payload1);
        assertArrayEquals(payload1, message.getRawPayload(), "getRawPayload should return the set payload");

        // Set another payload and verify
        byte[] payload2 = new byte[] { 1, 2, 3, 4, 5 };
        message.setRawPayload(payload2);

	NewStream(ctx context.Context, h HandlerID, payload []byte) (st *Stream, err error)
}

// Call the remove with the request and
func (h *StreamTypeHandler[Payload, Req, Resp]) Call(ctx context.Context, c Streamer, payload Payload) (st *TypedStream[Req, Resp], err error) {
	if c == nil {
		return nil, ErrDisconnected
	}
	var payloadB []byte
	if h.WithPayload {
		var err error

// https://docs.aws.amazon.com/AmazonS3/latest/API/images/s3select-frame-diagram-record.png
//
// Payload specification
// Records message payloads can contain a single record, partial records, or multiple records.
func newRecordsMessage(payload []byte) []byte {
	return genMessage(recordsHeader, payload)
}

// payloadLenForMsgLen computes the length of the payload in a record
// message given the total length of the message.

	var sub *subHandlerID
	if m.Payload == nil {
		m.Payload = GetByteBuffer()[:0]
	}
	h, err := m.UnmarshalMsg(b)
	if err != nil {
		return nil, nil, fmt.Errorf("read write: %v", err)
	}
	if len(m.Payload) == 0 && m.Flags&FlagPayloadIsZero == 0 {
		PutByteBuffer(m.Payload)
		m.Payload = nil
	}
	if m.Flags&FlagCRCxxh3 != 0 {
		const hashLen = 4

	b.Cleanup(grid.Cleanup)
	// Create n managers.
	for _, remote := range grid.Managers {
		// Register a single handler which echos the payload.
		errFatal(remote.RegisterSingleHandler(handlerTest, func(payload []byte) ([]byte, *RemoteErr) {
			defer PutByteBuffer(payload)
			return append(GetByteBuffer()[:0], payload...), nil
		}))
		errFatal(rpc.Register(remote, func(req *testRequest) (resp *testResponse, err *RemoteErr) {
			return &testResponse{

  /** Send a ping with the supplied [payload]. */
  @Throws(IOException::class)
  fun writePing(payload: ByteString) {
    writeControlFrame(OPCODE_CONTROL_PING, payload)
  }

  /** Send a pong with the supplied [payload]. */
  @Throws(IOException::class)
  fun writePong(payload: ByteString) {
    writeControlFrame(OPCODE_CONTROL_PONG, payload)
  }

  /**

  fun assertTextMessage(payload: String?) {
    assertThat(nextEvent()).isEqualTo(Message(string = payload))
  }

  fun assertBinaryMessage(payload: ByteString?) {
    assertThat(nextEvent()).isEqualTo(Message(payload))
  }

  fun assertPing(payload: ByteString) {
    assertThat(nextEvent()).isEqualTo(Ping(payload))
  }

  fun assertPong(payload: ByteString) {

	errFatal(local.RegisterSingleHandler(handlerTest, func(payload []byte) ([]byte, *RemoteErr) {
		t.Log("1: server payload: ", len(payload), "bytes.")
		return append([]byte{}, payload...), nil
	}))
	// 2: Return as error
	errFatal(local.RegisterSingleHandler(handlerTest2, func(payload []byte) ([]byte, *RemoteErr) {
		t.Log("2: server payload: ", len(payload), "bytes.")
		err := RemoteErr(payload)
		return nil, &err
	}))

The server handler function has this signature: `type SingleHandlerFn func(payload []byte) ([]byte, *RemoteErr)`.

Sample handler:
```go
    handler :=  func(payload []byte) ([]byte, *grid.RemoteErr) {
        // Do something with payload
        return []byte("response"), nil
    }

    err := manager.RegisterSingleHandler(grid.HandlerDiskInfo, handler)
```

func (c *Connection) sendMsg(conn net.Conn, msg message, payload msgp.MarshalSizer) error {
	if payload != nil {
		if sz := payload.Msgsize(); cap(msg.Payload) < sz {
			PutByteBuffer(msg.Payload)
			msg.Payload = GetByteBufferCap(sz)[:0]
		}
		var err error
		msg.Payload, err = payload.MarshalMsg(msg.Payload)
		if err != nil {
			return err
		}
		defer PutByteBuffer(msg.Payload)
	}
	dst := GetByteBufferCap(msg.Msgsize())