title: I want to use the "required" word as variable name in .proto file
body: <p>My proto file looks something like:</p>
  <pre><code>message Ack {
      bool required = 1;
      optional string address = 2;
  }
  </code></pre>
  <p>It looks like I am not able to name my variable as 'required' because its already been reserved by GRPC server system. Can anyone please guide me how to create a variable that has a name &quot;required&quot; instead of requiring a variable?</p>