36 files declare their use of RenderElement

Actions.php in core/lib/Drupal/Core/Render/Element/Actions.php
BreakLockLink.php in core/lib/Drupal/Core/TempStore/Element/BreakLockLink.php
ComponentElement.php in core/lib/Drupal/Core/Render/Element/ComponentElement.php
Container.php in core/lib/Drupal/Core/Render/Element/Container.php
ContextualLinks.php in core/modules/contextual/src/Element/ContextualLinks.php
ContextualLinksPlaceholder.php in core/modules/contextual/src/Element/ContextualLinksPlaceholder.php
Deprecated.php in core/modules/system/tests/modules/element_info_test/src/Element/Deprecated.php
DeprecatedExtendsRenderElement.php in core/modules/system/tests/modules/element_info_test/src/Element/DeprecatedExtendsRenderElement.php
Details.php in core/lib/Drupal/Core/Render/Element/Details.php
Dropbutton.php in core/lib/Drupal/Core/Render/Element/Dropbutton.php
ElementInfoManager.php in core/lib/Drupal/Core/Render/ElementInfoManager.php
Fieldgroup.php in core/lib/Drupal/Core/Render/Element/Fieldgroup.php
Fieldset.php in core/lib/Drupal/Core/Render/Element/Fieldset.php
FieldUiTable.php in core/modules/field_ui/src/Element/FieldUiTable.php
Form.php in core/lib/Drupal/Core/Render/Element/Form.php
Html.php in core/lib/Drupal/Core/Render/Element/Html.php
HtmlTag.php in core/lib/Drupal/Core/Render/Element/HtmlTag.php
InlineTemplate.php in core/lib/Drupal/Core/Render/Element/InlineTemplate.php
Label.php in core/lib/Drupal/Core/Render/Element/Label.php
LayoutBuilder.php in core/modules/layout_builder/src/Element/LayoutBuilder.php
Link.php in core/lib/Drupal/Core/Render/Element/Link.php
MoreLink.php in core/lib/Drupal/Core/Render/Element/MoreLink.php
Operations.php in core/lib/Drupal/Core/Render/Element/Operations.php
Page.php in core/lib/Drupal/Core/Render/Element/Page.php
Pager.php in core/lib/Drupal/Core/Render/Element/Pager.php
PageTitle.php in core/lib/Drupal/Core/Render/Element/PageTitle.php
ProcessedText.php in core/modules/filter/src/Element/ProcessedText.php
ResponsiveImage.php in core/modules/responsive_image/src/Element/ResponsiveImage.php
StatusMessages.php in core/lib/Drupal/Core/Render/Element/StatusMessages.php
StatusReport.php in core/lib/Drupal/Core/Render/Element/StatusReport.php
StatusReportPage.php in core/modules/system/src/Element/StatusReportPage.php
SystemCompactLink.php in core/lib/Drupal/Core/Render/Element/SystemCompactLink.php
TextFormat.php in core/modules/filter/src/Element/TextFormat.php
Toolbar.php in core/modules/toolbar/src/Element/Toolbar.php
ToolbarItem.php in core/modules/toolbar/src/Element/ToolbarItem.php
View.php in core/modules/views/src/Element/View.php

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