6 files declare their use of RouteBuildEvent

AccessSubscriber.php in drupal/core/lib/Drupal/Core/EventSubscriber/AccessSubscriber.php
Contains Drupal\Core\EventSubscriber\AccessSubscriber.
DisplayPageTest.php in drupal/core/modules/views/lib/Drupal/views/Tests/Plugin/DisplayPageTest.php
Contains \Drupal\views\Tests\Plugin\DisplayPageTest.
RouteSubscriber.php in drupal/core/modules/views/lib/Drupal/views/EventSubscriber/RouteSubscriber.php
Contains \Drupal\views\EventSubscriber\RouteSubscriber.
RouteSubscriber.php in drupal/core/modules/field_ui/lib/Drupal/field_ui/Routing/RouteSubscriber.php
Contains \Drupal\field_ui\Routing\RouteSubscriber.
RouteSubscriber.php in drupal/core/modules/rest/lib/Drupal/rest/EventSubscriber/RouteSubscriber.php
RouteTestSubscriber.php in drupal/core/modules/system/tests/modules/router_test/lib/Drupal/router_test/RouteTestSubscriber.php