Some types generated from `oneof` should always be required?

[mkfsn]

Hi folks, when started using grpc-web, I found that some types are always required in AsObject, but I'm wondering shouldn't they be optional?

Problem

Here's the repo I created to explain the problem I have: https://github.com/mkfsn/protoc-gen-grpc-web-oneof

I first define the message like this:

message Echo {
  string id = 1;
  int64 type = 2;

  oneof element {
    string text = 16;
    double numeric = 17;
  }
}

(See also: https://github.com/mkfsn/protoc-gen-grpc-web-oneof/blob/d0df6d0a3c526491373d5ab24a539c2ac2c7efc7/echo.proto#L7-L10)

And then I run the command to generate the typescript file:

protoc -I=. echo.proto \
		--grpc-web_out=import_style=typescript,mode=grpcwebtext:.

(See also: https://github.com/mkfsn/protoc-gen-grpc-web-oneof/blob/main/Makefile#L2-L3)

After that I'm getting the following results in the _pb.d.ts file:

export namespace Echo {
  export type AsObject = {
    id: string,
    type: number,
    text: string,
    numeric: number,
  }

  export enum ElementCase { 
    ELEMENT_NOT_SET = 0,
    TEXT = 16,
    NUMERIC = 17,
  }
}

(See also: https://github.com/mkfsn/protoc-gen-grpc-web-oneof/blob/d0df6d0a3c526491373d5ab24a539c2ac2c7efc7/echo_pb.d.ts#L32-L33)

I'm wondering shouldn't text and numeric be optional like:

    text?: string,
    numeric?: number,

I'm using version grpc-web 1.2.1 and using macos.

I'm not sure if this is intended or not, can anyone confirm this with me? Sorry if I'm wrong.