Please, update Your code to avoid such notifications.
The Symfony\Component\Security\Core\SecurityContext class is deprecated since version 2.6 and will be removed in 3.0:
./vendor/ftrrtf/rollbar-bundle/EventListener/RollbarListener.php
./vendor/ftrrtf/rollbar-bundle/spec/Ftrrtf/RollbarBundle/EventListener/RollbarListenerSpec.php
Please, update Your code to avoid such notifications.
v0.15.2 Thank You