Where to start learning ScalaPB?

I am new to scalaPB, Grpc, and Protobuf concepts. In my present project I need ScalaPB for implementing Grpc services. But I do not found any doc's regarding the Service and Server implementation (especially for repeated modifier). Could you please help we with the service implementation for repeated request field and repeated replay field. Thanks you.

    message IOTDecodeRequest {
  string id = 1;
  string device_id = 2;
  string device_parser_id = 3;
  bytes raw_data = 4;
}

message IOTDecodeResult {
  google.protobuf.Struct decoded = 1;
}

message IOTDecodeResponse {
  int32 status = 1;
  string id = 2;
  IOTDecodeResult result = 3;
  IOTDecodeError error = 4;
}

message IOTDecodeError {
  int32 code = 1;
  string message = 2;
  string details = 3;
}

message IOTDecodeRequests {
  repeated IOTDecodeRequest requests = 1;
}

message IOTDecodeResponses {
  repeated IOTDecodeResponse responses = 2;
}

service IoTDecoderService {
  rpc Decode(IOTDecodeRequests) returns (IOTDecodeResponses);
}