40 files declare their use of ThemeHandlerInterface

BasicSettingsForm.php in core/modules/views_ui/src/Form/BasicSettingsForm.php
BlockConfigEntityUnitTest.php in core/modules/block/tests/src/Unit/BlockConfigEntityUnitTest.php
BlockContentController.php in core/modules/block_content/src/Controller/BlockContentController.php
BlockController.php in core/modules/block/src/Controller/BlockController.php
BlockForm.php in core/modules/block/src/BlockForm.php
BlockListController.php in core/modules/block/src/Controller/BlockListController.php
BreakpointManager.php in core/modules/breakpoint/src/BreakpointManager.php
CKEditor5StylesheetsMessage.php in core/modules/ckeditor5/src/CKEditor5StylesheetsMessage.php
ComponentPluginManager.php in core/lib/Drupal/Core/Theme/ComponentPluginManager.php
ComponentPluginManager.php in core/modules/sdc/src/ComponentPluginManager.php
ConfigCacheTag.php in core/modules/system/src/EventSubscriber/ConfigCacheTag.php
ConfigEntityBaseUnitTest.php in core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php
ConfigImporter.php in core/lib/Drupal/Core/Config/ConfigImporter.php
ConfigMapperManager.php in core/modules/config_translation/src/ConfigMapperManager.php
ConfigSingleImportForm.php in core/modules/config/src/Form/ConfigSingleImportForm.php
ConfigSync.php in core/modules/config/src/Form/ConfigSync.php
ConfigTranslationBlockListBuilder.php in core/modules/config_translation/src/Controller/ConfigTranslationBlockListBuilder.php
CurrentThemeCondition.php in core/modules/system/src/Plugin/Condition/CurrentThemeCondition.php
DbUpdateNegotiator.php in core/modules/system/src/Theme/DbUpdateNegotiator.php
ElementInfoManager.php in core/lib/Drupal/Core/Render/ElementInfoManager.php
ElementInfoManagerTest.php in core/tests/Drupal/Tests/Core/Render/ElementInfoManagerTest.php
ExtensionExistsConstraintValidator.php in core/lib/Drupal/Core/Extension/Plugin/Validation/Constraint/ExtensionExistsConstraintValidator.php
FilesystemLoader.php in core/lib/Drupal/Core/Template/Loader/FilesystemLoader.php
HelpTopicPluginManager.php in core/modules/help/src/HelpTopicPluginManager.php
HelpTopicTwigLoader.php in core/modules/help/src/HelpTopicTwigLoader.php
HelpTopicTwigLoaderTest.php in core/modules/help/tests/src/Unit/HelpTopicTwigLoaderTest.php
LayoutPluginManager.php in core/lib/Drupal/Core/Layout/LayoutPluginManager.php
LayoutPluginManagerTest.php in core/tests/Drupal/Tests/Core/Layout/LayoutPluginManagerTest.php
NegotiationConfigureForm.php in core/modules/language/src/Form/NegotiationConfigureForm.php
PluginDependencyTraitTest.php in core/tests/Drupal/Tests/Core/Plugin/PluginDependencyTraitTest.php
Registry.php in core/lib/Drupal/Core/Theme/Registry.php
ThemeAccessCheck.php in core/lib/Drupal/Core/Theme/ThemeAccessCheck.php
ThemeController.php in core/modules/system/src/Controller/ThemeController.php
ThemeInitialization.php in core/lib/Drupal/Core/Theme/ThemeInitialization.php
ThemeLocalTask.php in core/modules/block/src/Plugin/Derivative/ThemeLocalTask.php
ThemeLocalTask.php in core/modules/system/src/Plugin/Derivative/ThemeLocalTask.php
ThemeSettingsForm.php in core/modules/system/src/Form/ThemeSettingsForm.php
UpdateManager.php in core/modules/update/src/UpdateManager.php
UpdateRegistry.php in core/lib/Drupal/Core/Update/UpdateRegistry.php
UpdateRegistryTest.php in core/tests/Drupal/Tests/Core/Update/UpdateRegistryTest.php

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