title: asp.net core how to add claims to User
body: <p>I am using ASP.NET Core 2.0, with Azure AD v2.0 endpoint. 
  I am getting claims like this:</p>
  
  <pre><code>var currentUser = User;
  
  var displayName = currentUser.FindFirst("name").Value;
  var claims = currentUser.Claims;
  </code></pre>
  
  <p>I am not used to using this <code>User</code> to get claims, but could not get the old way with <code>System.Security.Claims</code> to work. So my first question is, is this how I should be getting my claims? And my second question is, how do I add claims to this <code>User</code>?</p>