Version 5.0.6

system/Login/Handler/Handler.php

@@ -679,13 +679,13 @@ abstract class Handler extends Model
 	 * May return NULL if server doesn't support this
 	 *
 	 * @param string $identifier	The ID Nnumber/string from remote service
-	 * @param string $username	The username from remote service
+	 * @param string|null $username	The username from remote service
 	 * @return	Url|NULL
 	 * @throws    Exception    The token is invalid and the user needs to reauthenticate
 	 * @throws	DomainException		General error where it is safe to show a message to the user
 	 * @throws	RuntimeException		Unexpected error from service
 	 */
-	public function userLink( string $identifier, string $username ): ?Url
+	public function userLink( string $identifier, ?string $username ): ?Url
 	{
 		return NULL;
 	}