6 files declare their use of AccessAwareRouterInterface in Drupal 9

AccessAwareRouterTest.php in core/tests/Drupal/Tests/Core/Routing/AccessAwareRouterTest.php

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

CustomPageExceptionHtmlSubscriberTest.php in core/tests/Drupal/Tests/Core/EventSubscriber/CustomPageExceptionHtmlSubscriberTest.php

EntityResource.php in core/modules/rest/src/Plugin/rest/resource/EntityResource.php

PathValidator.php in core/lib/Drupal/Core/Path/PathValidator.php

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