28 files declare their use of Section

AddSectionController.php in core/modules/layout_builder/src/Controller/AddSectionController.php
ConfigureSectionForm.php in core/modules/layout_builder/src/Form/ConfigureSectionForm.php
DefaultsSectionStorageTest.php in core/modules/layout_builder/tests/src/Kernel/DefaultsSectionStorageTest.php
EntityViewDisplayValidationTest.php in core/tests/Drupal/KernelTests/Core/Entity/EntityViewDisplayValidationTest.php
LayoutBuilderEntityViewDisplay.php in core/modules/layout_builder/src/Entity/LayoutBuilderEntityViewDisplay.php
LayoutBuilderEntityViewDisplayStorage.php in core/modules/layout_builder/src/Entity/LayoutBuilderEntityViewDisplayStorage.php
LayoutBuilderFieldLayoutCompatibilityTest.php in core/modules/layout_builder/tests/src/Kernel/LayoutBuilderFieldLayoutCompatibilityTest.php
LayoutBuilderInstallTest.php in core/modules/layout_builder/tests/src/Kernel/LayoutBuilderInstallTest.php
LayoutBuilderTest.php in core/modules/layout_builder/tests/src/Functional/LayoutBuilderTest.php
LayoutEntityHelperTraitTest.php in core/modules/layout_builder/tests/src/Kernel/LayoutEntityHelperTraitTest.php
LayoutEntityHelperTraitTest.php in core/modules/layout_builder/tests/src/Unit/LayoutEntityHelperTraitTest.php
LayoutSectionItem.php in core/modules/layout_builder/src/Plugin/Field/FieldType/LayoutSectionItem.php
LayoutSectionItemList.php in core/modules/layout_builder/src/Field/LayoutSectionItemList.php
LayoutSectionTest.php in core/modules/layout_builder/tests/src/Functional/LayoutSectionTest.php
layout_builder.install in core/modules/layout_builder/layout_builder.install
Contains install and update functions for Layout Builder.
NavigationSectionStorage.php in core/modules/navigation/src/Plugin/SectionStorage/NavigationSectionStorage.php
OverridesSectionStorageTest.php in core/modules/layout_builder/tests/src/Kernel/OverridesSectionStorageTest.php
SectionData.php in core/modules/layout_builder/src/Plugin/DataType/SectionData.php
SectionListTestBase.php in core/modules/layout_builder/tests/src/Kernel/SectionListTestBase.php
SectionListTraitTest.php in core/modules/layout_builder/tests/src/Kernel/SectionListTraitTest.php
SectionRenderTest.php in core/modules/layout_builder/tests/src/Unit/SectionRenderTest.php
SectionStorageBase.php in core/modules/layout_builder/src/Plugin/SectionStorage/SectionStorageBase.php
SectionTest.php in core/modules/layout_builder/tests/src/Unit/SectionTest.php
SimpleConfigSectionListTest.php in core/modules/layout_builder/tests/src/Kernel/SimpleConfigSectionListTest.php
SimpleConfigSectionStorage.php in core/modules/layout_builder/tests/modules/layout_builder_test/src/Plugin/SectionStorage/SimpleConfigSectionStorage.php
TestPrepareLayout.php in core/modules/layout_builder/tests/modules/layout_builder_element_test/src/EventSubscriber/TestPrepareLayout.php
TestStateBasedSectionStorage.php in core/modules/layout_builder/tests/modules/layout_builder_test/src/Plugin/SectionStorage/TestStateBasedSectionStorage.php
TranslatableFieldTest.php in core/modules/layout_builder/tests/src/Kernel/TranslatableFieldTest.php

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