title: IdentityServer3 - how to get partial identity in PreAuthenticateAsync?
body: <p>Question is quite self-describing. There is method:</p>
  
  <pre><code>await this.owinContext.Environment.GetIdentityServerPartialLoginAsync();
  </code></pre>
  
  <p>But in <code>PreAuthenticateAsync</code> method it gets <code>null</code> result. As a way how to achieve partial identity I use redirect to one of my controllers and back, but is there better way?</p>