7 files declare their use of ConfigImporterEvent in Drupal 9

BundleConfigImportValidate.php in core/lib/Drupal/Core/Entity/Event/BundleConfigImportValidate.php

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

ConfigImportSubscriber.php in core/modules/content_moderation/src/EventSubscriber/ConfigImportSubscriber.php

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

ConfigSubscriber.php in core/modules/config/src/ConfigSubscriber.php

EventSubscriber.php in core/modules/config/tests/config_import_test/src/EventSubscriber.php

SystemConfigSubscriber.php in core/modules/system/src/SystemConfigSubscriber.php