title: Why is ClaimTypes.NameIdentifier not mapping to 'sub'?
body: <p>Using ASP.NET Core 2.2 and Identity Server 4 I have the following controller:</p>
  
  <pre><code>[HttpGet("posts"), Authorize]
  public async Task&lt;IActionResult&gt; GetPosts() {
  
    var authenticated = this.User.Identity.IsAuthenticated;
  
    var claims = this.User.Identities.FirstOrDefault().Claims;
  
    var id = this.User.FindFirstValue(ClaimTypes.NameIdentifier);
  
  }
  </code></pre>
  
  <p>I get all the <code>claims</code> but <code>id</code> is null ... </p>
  
  <p>I checked all values in <code>claims</code> and I have a 'sub' claim with value 1.</p>
  
  <p>Why is ClaimTypes.NameIdentifier not mapping to 'sub'?</p>