[Security] fixed wrong phpdoc

src/Symfony/Component/Security/Core/Authentication/Token/TokenInterface.php

@@ -47,8 +47,10 @@ interface TokenInterface extends \Serializable
     /**
      * Returns a user representation.
      *
-     * @return mixed either returns an object which implements __toString(), or
-     *               a primitive string is returned.
+     * @return mixed Can be a UserInterface instance, an object implementing a __toString method,
+     *               or the username as a regular string
+     *
+     * @see AbstractToken::setUser()
      */
     public function getUser();