title: protobuf.js pbts: Generating typescript types from .proto without null | undefined
body: <p>I'm using pbts to generate typescript declaration files for a large protobuf library. </p>
  
  <p>The problem is that the pbts output makes every property undefined or null, e.g.</p>
  
  <p><code>interface IMyThing {
     myProp?: string | null;
  }
  </code>
  and what I want is:</p>
  
  <p><code>interface IMyThing {
      myProp: string;
  }
  </code></p>
  
  <p>The actual protobuf definitions are NOT optional. They look like:</p>
  
  <p><code>message MyThing {
      string myProp = 1;
  }
  </code></p>
  
  <p>Is there some flag or way to adjust the source code of pbts or post-process its output, so that I can remove these incorrect undefined/null attributes?</p>