20 files declare their use of FileStorage

CachedStorageTest.php in core/tests/Drupal/KernelTests/Core/Config/Storage/CachedStorageTest.php
comment.post_update.php in core/modules/comment/comment.post_update.php
Post update functions for the comment module.
ConfigAfterInstallerTestBase.php in core/tests/Drupal/FunctionalTests/Installer/ConfigAfterInstallerTestBase.php
ConfigAfterInstallerTestBase.php in core/modules/system/src/Tests/Installer/ConfigAfterInstallerTestBase.php
ConfigFileContentTest.php in core/tests/Drupal/KernelTests/Core/Config/ConfigFileContentTest.php
ConfigInstallProfileOverrideTest.php in core/modules/config/tests/src/Functional/ConfigInstallProfileOverrideTest.php
ConfigSchemaTest.php in core/tests/Drupal/KernelTests/Core/Config/ConfigSchemaTest.php
dblog.post_update.php in core/modules/dblog/dblog.post_update.php
Post update functions for the Database Logging module.
DefaultConfigTest.php in core/tests/Drupal/KernelTests/Config/DefaultConfigTest.php
DemoUmamiProfileTest.php in core/profiles/demo_umami/tests/src/Functional/DemoUmamiProfileTest.php
FileStorageFactoryTest.php in core/tests/Drupal/KernelTests/Core/Config/FileStorageFactoryTest.php
FileStorageTest.php in core/tests/Drupal/KernelTests/Core/Config/Storage/FileStorageTest.php
FunctionalTestSetupTrait.php in core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php
install.core.inc in core/includes/install.core.inc
API functions for installing Drupal.
MediaDisplayTest.php in core/modules/media/tests/src/FunctionalJavascript/MediaDisplayTest.php
ModuleTestBase.php in core/modules/system/tests/src/Functional/Module/ModuleTestBase.php
ModuleTestBase.php in core/modules/system/src/Tests/Module/ModuleTestBase.php
SelectProfileForm.php in core/lib/Drupal/Core/Installer/Form/SelectProfileForm.php
ViewsConfigUpdaterTest.php in core/modules/views/tests/src/Kernel/ViewsConfigUpdaterTest.php
ViewTestData.php in core/modules/views/src/Tests/ViewTestData.php

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