title: Will refresh token expire once 2FA is enabled
body: <p>We generated a refresh token with the following C# code snippet:</p>
  <pre class="lang-cs prettyprint-override"><code>public IActionResult GetGoogleToken()
  {
      UserCredential credentials = GoogleWebAuthorizationBroker.AuthorizeAsync(
          new ClientSecrets()
          {
              ClientId = &quot;CLIENT_ID&quot;,
              ClientSecret = &quot;CLIENT_SECRET&quot;
          },
          new string[] { GmailService.Scope.GmailReadonly },
          &quot;user&quot;,
          CancellationToken.None,
          new NullDataStore()).Result;
  
      return Json(credentials.Token.RefreshToken);
  }
  </code></pre>
  <p>Since then, we have been using it to fetch emails using Gmail API:</p>
  <pre class="lang-cs prettyprint-override"><code>private async Task&lt;GmailService&gt; GetGmailService()
  {
      UserCredential credentials = new UserCredential(
          new GoogleAuthorizationCodeFlow(
              new GoogleAuthorizationCodeFlow.Initializer
              {
                  ClientSecrets = new ClientSecrets()
                  {
                      ClientId = &quot;CLIENT_ID&quot;,
                      ClientSecret = &quot;CLIENT_SECRET&quot;
                  }
              }),
          &quot;user&quot;,
          REFRESH_TOKEN
      );
      
      if (credentials.Token.IsExpired(SystemClock.Default))
      {
          if (!await credentials.RefreshTokenAsync(CancellationToken.None))
          {
              throw new Exception(&quot;Token could not be refreshed&quot;);
          }
      }
  
      return new GmailService(new BaseClientService.Initializer()
      {
          HttpClientInitializer = credentials,
          ApplicationName = &quot;APP&quot;,
      });
  }
  </code></pre>
  <p>My question is: Will the refresh token expire once we enable 2FA on the account? Is this behavior documented anywhere?</p>