Expanded class hierarchy of ContainerAwareTraceableEventDispatcher

class \Symfony\Component\EventDispatcher\EventDispatcher implements EventDispatcherInterface
- class \Symfony\Component\EventDispatcher\ContainerAwareEventDispatcher
  - class \Symfony\Component\HttpKernel\Debug\ContainerAwareTraceableEventDispatcher implements TraceableEventDispatcherInterface
- class \Symfony\Component\HttpKernel\Tests\Fixtures\TestEventDispatcher implements TraceableEventDispatcherInterface