20 files declare their use of ConfigEvents in Drupal 8

BcConfigSubscriber.php in core/modules/serialization/src/EventSubscriber/BcConfigSubscriber.php

ColorConfigCacheInvalidator.php in core/modules/color/src/EventSubscriber/ColorConfigCacheInvalidator.php

ConfigCacheTag.php in core/modules/system/src/EventSubscriber/ConfigCacheTag.php

ConfigEventsTest.php in core/tests/Drupal/KernelTests/Core/Config/ConfigEventsTest.php

ConfigSchemaChecker.php in core/lib/Drupal/Core/Config/Development/ConfigSchemaChecker.php

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

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

ConfigSubscriber.php in core/modules/language/src/EventSubscriber/ConfigSubscriber.php

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

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

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

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

FinalMissingContentSubscriber.php in core/lib/Drupal/Core/Config/Importer/FinalMissingContentSubscriber.php

LocaleConfigSubscriber.php in core/modules/locale/src/LocaleConfigSubscriber.php

MediaConfigSubscriber.php in core/modules/media/src/EventSubscriber/MediaConfigSubscriber.php

NodeAdminRouteSubscriber.php in core/modules/node/src/EventSubscriber/NodeAdminRouteSubscriber.php

QueryFactory.php in core/lib/Drupal/Core/Config/Entity/Query/QueryFactory.php

RestConfigSubscriber.php in core/modules/rest/src/EventSubscriber/RestConfigSubscriber.php

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

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