Fixed the phpDoc of UserInterface

src/Symfony/Component/Security/Core/User/UserInterface.php

@@ -47,7 +47,7 @@ interface UserInterface
      * and populated in any number of different ways when the user object
      * is created.
      *
-     * @return Role[] The user roles
+     * @return (Role|string)[] The user roles
      */
     public function getRoles();