26 files declare their use of ModuleExtensionList

AdminController.php in core/modules/system/src/Controller/AdminController.php
CKEditor.php in core/modules/ckeditor/src/Plugin/Editor/CKEditor.php
CKEditorPluginBase.php in core/modules/ckeditor/src/CKEditorPluginBase.php
ConfigImporter.php in core/lib/Drupal/Core/Config/ConfigImporter.php
ConfigImportSubscriber.php in core/lib/Drupal/Core/EventSubscriber/ConfigImportSubscriber.php
ConfigSingleImportForm.php in core/modules/config/src/Form/ConfigSingleImportForm.php
ConfigSync.php in core/modules/config/src/Form/ConfigSync.php
DrupalMedia.php in core/modules/ckeditor/src/Plugin/CKEditorPlugin/DrupalMedia.php
DrupalMediaLibrary.php in core/modules/ckeditor/src/Plugin/CKEditorPlugin/DrupalMediaLibrary.php
HelpController.php in core/modules/help/src/Controller/HelpController.php
InstallerModuleExtensionList.php in core/lib/Drupal/Core/Installer/InstallerModuleExtensionList.php
LegacyExtensionPathResolverTest.php in core/tests/Drupal/KernelTests/Core/Extension/LegacyExtensionPathResolverTest.php
LoadLibraryController.php in core/modules/system/tests/modules/modernizr_deprecation_test/src/Controller/LoadLibraryController.php
ModuleRequiredByThemesUninstallValidatorTest.php in core/tests/Drupal/Tests/Core/Extension/ModuleRequiredByThemesUninstallValidatorTest.php
ModulesListForm.php in core/modules/system/src/Form/ModulesListForm.php
ModulesListNonStableConfirmForm.php in core/modules/system/src/Form/ModulesListNonStableConfirmForm.php
ModulesUninstallConfirmForm.php in core/modules/system/src/Form/ModulesUninstallConfirmForm.php
ModulesUninstallForm.php in core/modules/system/src/Form/ModulesUninstallForm.php
Registry.php in core/lib/Drupal/Core/Theme/Registry.php
RegistryLegacyTest.php in core/tests/Drupal/Tests/Core/Theme/RegistryLegacyTest.php
RegistryTest.php in core/tests/Drupal/KernelTests/Core/Theme/RegistryTest.php
RegistryTest.php in core/tests/Drupal/Tests/Core/Theme/RegistryTest.php
SecurityAdvisoriesFetcher.php in core/modules/system/src/SecurityAdvisories/SecurityAdvisoriesFetcher.php
SecurityAdvisoriesFetcherTest.php in core/modules/system/tests/src/Kernel/SecurityAdvisories/SecurityAdvisoriesFetcherTest.php
SystemController.php in core/modules/system/src/Controller/SystemController.php
UpdateManager.php in core/modules/update/src/UpdateManager.php

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