title: Protobuf message common attributes wrapper
body: <p>We have protobuf messages which share common attributes, for example</p>
  <pre><code>message Message1 {
      string foo = 1;
      string bar = 2;
      string baz = 3;
      string custom1 = 4;
  }
  
  message Message2 {
      string foo = 1;
      string bar = 2;
      string baz = 3;
      string custom2 = 4;
  }
  
  message Message3 {
      string foo = 1;
      string bar = 2;
      string baz = 3;
      string custom3 = 4;
  }
  
  message Message4 {
      string foo = 1;
      string bar = 2;
      string baz = 3;
      string custom4 = 4;
  }
  </code></pre>
  <p>How can we have the common attributes defined in a separate proto file and be reused in all the messages.</p>
  <pre><code>message MessageCommonFields {
      string foo = 1;
      string bar = 2;
      string baz = 3;
  }
  </code></pre>