code: public static Message buildRequest(ByteBuffer request) {
      Request req = Request.newBuilder()
                           .setRequest(ByteString.copyFrom(request))
                           .build();
  
      return Message.newBuilder().setType(MessageType.REQUEST)
                                 .setRequest(req)
                                 .build();
    }
docs: Creates a REQUEST message.
  
  @param request the ByteBuffer represents the request.
  @return a protobuf message.