title: Stopping omission of default values in Protocol Buffers
body: <p>I have a proto schema defined as below,</p>
  
  <pre><code>message User {
     int64 id = 1;
     bool email_subscribed = 2;
     bool sms_subscribed = 3;
  }
  </code></pre>
  
  <p>Now as per official <a href="https://developers.google.com/protocol-buffers/docs/proto3#json" rel="noreferrer">proto3 documentation</a>, default values are not serialized to save space during wire transmission. But in my case I want to receive whether the client has explicitly set <code>true/false</code> for fields <code>email_subscribed/sms_subscribed</code> (because the values were <code>true</code> before but now the user wants to unsubscribe). Hence, when the client sends <code>false</code> for any of these fields, the generator code serializer just omits these fields.</p>
  
  <p>How do I achieve this and avoid the omission of these fields for the above scenario?</p>
  
  <p>PS: I am using Javascript as my GRPC client and Python and GRPC Server.</p>