12 files declare their use of FieldUI

DefaultsSectionStorage.php in core/modules/layout_builder/src/Plugin/SectionStorage/DefaultsSectionStorage.php
EntityDisplayFormBase.php in core/modules/field_ui/src/Form/EntityDisplayFormBase.php
EntityFormDisplayEditForm.php in core/modules/field_ui/src/Form/EntityFormDisplayEditForm.php
EntityViewDisplayEditForm.php in core/modules/field_ui/src/Form/EntityViewDisplayEditForm.php
FieldConfigDeleteForm.php in core/modules/field_ui/src/Form/FieldConfigDeleteForm.php
FieldConfigEditForm.php in core/modules/field_ui/src/Form/FieldConfigEditForm.php
FieldStorageAddForm.php in core/modules/field_ui/src/Form/FieldStorageAddForm.php
FieldStorageConfigEditForm.php in core/modules/field_ui/src/Form/FieldStorageConfigEditForm.php
FieldUiTest.php in core/modules/field_ui/tests/src/Unit/FieldUiTest.php
field_ui.module in core/modules/field_ui/field_ui.module
Allows administrators to attach custom fields to fieldable types.
MediaLibraryWidget.php in core/modules/media_library/src/Plugin/Field/FieldWidget/MediaLibraryWidget.php
WidgetWithoutTypesTest.php in core/modules/media_library/tests/src/FunctionalJavascript/WidgetWithoutTypesTest.php

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