How can i use protobuf with rsocket (I don't want to use RPC architecture)

Hello. I am new in rsocket world. How can i send data using protobuf from angular app to spring app?
I have something like this but it doesn’t work (client doesn’t send anything):

this.client = new RSocketClient({
        serializers: {
            data: IdentitySerializer,
            metadata: IdentitySerializer
        },
        setup: {
            // ms btw sending keepalive to server
            keepAlive: 60000,
            // ms timeout if no keepalive response
            lifetime: 180000,
            // format of `data`
            dataMimeType: 'application/octet-stream',
            // format of `metadata`
            metadataMimeType: 'message/x.rsocket.routing.v0',
            payload: {
                data: this.formatter.prepareNicknamePayload(this.myNickname)
            }
        },
        transport: new RSocketWebSocketClient({
            url: this.serverUrl
        })
    });

Proto file:

syntax = "proto3";

message PlayerProto {
       string nickname = 1;
       int32 position_x = 2;
       int32 position_y = 3;
       int32 score = 4;
       string step_direction = 5;
       int32 version = 6;}

Here i parse my json data into generated object:

    encode(data): PlayerProto {
           const playerProto = new PlayerProto();
           playerProto.setNickname(data.nickname);
           playerProto.setPositionX(data.positionX);
           playerProto.setPositionY(data.positionY);
           playerProto.setScore(data.score);
           playerProto.setStepDirection(data.stepDirection);
           playerProto.setVersion(data.version);

           return playerProto;
}

And here i try to send data:

const encodedData = this.formatter.encode(dataToSend);
    this.rsocketObject.fireAndForget({
        data: encodedData.serializeBinary(), // Uint8Array
        metadata: String.fromCharCode('sendPositionProtobuf'.length) + 'sendPositionProtobuf',
    });

Spring application controller:

    @MessageMapping("sendPositionProtobuf")
    public void updatePositionForPlayer(byte[] bytes) { .... }

Config:

spring.rsocket.server.port=8080
spring.rsocket.server.transport=websocket
spring.rsocket.server.mapping-path=/rsocket