6 files declare their use of FilterControllerEvent in Zircon Profile 8

EarlyRenderingControllerWrapperSubscriber.php in core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php

Contains \Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber.

HttpKernel.php in vendor/symfony/http-kernel/HttpKernel.php

PathSubscriber.php in core/lib/Drupal/Core/EventSubscriber/PathSubscriber.php

Contains \Drupal\Core\EventSubscriber\PathSubscriber.

RequestDataCollector.php in vendor/symfony/http-kernel/DataCollector/RequestDataCollector.php

RequestDataCollectorTest.php in vendor/symfony/http-kernel/Tests/DataCollector/RequestDataCollectorTest.php

RouterDataCollector.php in vendor/symfony/http-kernel/DataCollector/RouterDataCollector.php