as of SF2.6 the SecurityContextInterface is marked as deprecated
https://github.com/symfony/symfony/blob/2.7/UPGRADE-2.6.md#security
however Controller class is still using security.context in isGranted() function
https://github.com/symfony/symfony/blob/2.7/src/Symfony/Bundle/FrameworkBundle/Controller/Controller.php#L130

i think that this should be changed from security.context to security.authorization_checker