Include Login Hint in Authentication Properties

source/Core/Constants.cs

@@ -743,6 +743,7 @@ public static class Authentication
             public const string SigninId                    = "signinid";
             public const string SignoutId                   = "id";
             public const string KatanaAuthenticationType    = "katanaAuthenticationType";
+			public const string LoginHint    				= "login_hint";
             public const string PartialLoginRememberMe      = "idsvr:rememberme";
         }
 
@@ -797,4 +798,4 @@ public static class ClaimValueTypes
             OidcConstants.Algorithms.Asymmetric.PS512,
         };
     }
-}
+}

source/Core/Endpoints/AuthenticationController.cs

@@ -325,6 +325,12 @@ public async Task<IHttpActionResult> LoginExternal(string signin, string provide
             // add the id to the dictionary so we can recall the cookie id on the callback
             authProp.Dictionary.Add(Constants.Authentication.SigninId, signin);
             authProp.Dictionary.Add(Constants.Authentication.KatanaAuthenticationType, provider);
+
+			if (signInMessage.LoginHint.IsPresent())
+            {
+                authProp.Dictionary.Add(Constants.Authentication.LoginHint, signInMessage.LoginHint);
+            }
+
             context.Authentication.Challenge(authProp, provider);
 
             return Unauthorized();