newordersingle.proto

syntax = "proto3";

package FIX;
import "executionreport.proto";


message NewOrderSingle {
    string ClOrdID = 1;
    string Instrument = 2;

    enum TradeSide {
        BUY=0;
        SELL=1;
    }

    TradeSide Side = 3;
    uint32 OrdType = 4;
    string Price = 5;
    string StopPx = 6;
    string OrderQty = 7;
    uint32 TimeInForce = 8; 
    uint64 ExpireTime = 9; // in nanoseconds 
    string ExecInst = 10;
    string CancelOnDisconnect = 11;
}

message NewOrderSingleResult {
      
    repeated ExecutionReport execution_report = 1;
    string error = 2;
    uint32 response_code = 3;
}

service CreateOrder {
  rpc sendNewOrderSingle (NewOrderSingle) returns (NewOrderSingleResult) {}
}

required is a proto2 keyword, not proto3

https://stackoverflow.com/questions/31801257/why-required-and-optional-is-removed-in-protocol-buffers-3

Oops yeah updated thanks