title: Cognito authentication using federated identity does not create a user in the pool
body: <p>I'm using Cognito with a user pool to provide authentication for my Ionic application application. The application use AWS Amplify to perform the Signup and Signin operation. </p>
  
  <p>Now, I need to add facebook authentication so I added an external federated identity mapping also the facebook attributes to the corresponding Cognito user pool attributes.</p>
  
  <p>On the application side I use the Facebook SDK to login with Facebook, receive Facebook's JWT token and call the Amplify federatedSignIn() to authenticate. The authentication works but no user is created inside the Cognito user pool (accordingly to <a href="https://docs.aws.amazon.com/cognito/latest/developerguide/cognito-user-pools-configuring-federation-with-social-idp.html" rel="nofollow noreferrer">official documentation</a> "Whether your users sign in directly or through a third party, all users have a profile in the user pool").</p>
  
  <p>Since the user is not created I cannot call the Amplify method currentSession() to get the token (to be used for lambda authentication) since there is no user.</p>
  
  <p>Am I missing something?</p>