title: Is the Google Id/Subject string returned from a GoogleIDToken validation actually a number?
body: <p>I'm currently looking into server-side validation of a GoogleIDToken for Google Sign-in (Android &amp; iOS). <a href="https://developers.google.com/identity/sign-in/android/backend-auth#send-the-id-token-to-your-server" rel="nofollow">Documentation here</a></p>
  
  <p>In the example, the "sub" field in the object returned by the Google API endpoint is read as a string, but it looks like it may actually be a (really big) number.</p>
  
  <p>Some other tests using some users on my side also show big numbers.</p>
  
  <p>Looking deeper in the Payload documentation, it looks like this value could be null, but outside of this possibility, can we assume that this string is actually a number?</p>
  
  <p>This is important because we want to store it in a database, and saving it as a number might actually be more efficient than a string.</p>