7 files declare their use of HttpException in Zircon Profile 8

DBLogResource.php in core/modules/dblog/src/Plugin/rest/resource/DBLogResource.php

Contains \Drupal\dblog\Plugin\rest\resource\DBLogResource.

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

Contains \Drupal\rest\Plugin\rest\resource\EntityResource.

FormAjaxResponseBuilder.php in core/lib/Drupal/Core/Form/FormAjaxResponseBuilder.php

Contains \Drupal\Core\Form\FormAjaxResponseBuilder.

FormAjaxSubscriberTest.php in core/tests/Drupal/Tests/Core/Form/EventSubscriber/FormAjaxSubscriberTest.php

Contains \Drupal\Tests\Core\Form\EventSubscriber\FormAjaxSubscriberTest.

ProfilerListenerTest.php in vendor/symfony/http-kernel/Tests/EventListener/ProfilerListenerTest.php

RequestHandler.php in core/modules/rest/src/RequestHandler.php

Contains \Drupal\rest\RequestHandler.

Test.php in core/modules/system/tests/modules/test_page_test/src/Controller/Test.php

Contains \Drupal\test_page_test\Controller\Test.