E-Mail auto-populates in email field

js/issuer.js

@@ -400,6 +400,10 @@ $(function () {
           + '&error_uri=' + encodeURIComponent('https://oauth3.org/docs/errors/#E_IFRAME_DENIED');
         location.href = callbackUrl;
       }
+      if (clientParams.subject) {
+        $('.js-oauth3-email').val(clientParams.subject);
+        $('.js-authn-show').prop('disabled', false);
+      }
       $('.js-userid-container').show();
     }).then(function () {
       //$('body').addClass('in');