48 files declare their use of PluginBase

ActionBase.php in core/lib/Drupal/Core/Action/ActionBase.php
AggregatorPluginSettingsBase.php in core/modules/aggregator/src/Plugin/AggregatorPluginSettingsBase.php
BlockBase.php in core/lib/Drupal/Core/Block/BlockBase.php
Breakpoint.php in core/modules/breakpoint/src/Breakpoint.php
Broken.php in core/lib/Drupal/Core/Block/Plugin/Block/Broken.php
CKEditor5PluginDefault.php in core/modules/ckeditor5/src/Plugin/CKEditor5PluginDefault.php
CKEditorPluginBase.php in core/modules/ckeditor/src/CKEditorPluginBase.php
ConfigNamesMapper.php in core/modules/config_translation/src/ConfigNamesMapper.php
ContextAwarePluginTraitTest.php in core/tests/Drupal/KernelTests/Core/Plugin/Context/ContextAwarePluginTraitTest.php
ContextHandlerTest.php in core/tests/Drupal/KernelTests/Core/Plugin/ContextHandlerTest.php
Contrib.php in core/modules/ckeditor5/src/Plugin/CKEditor4To5Upgrade/Contrib.php
Core.php in core/modules/ckeditor5/src/Plugin/CKEditor4To5Upgrade/Core.php
DestinationBase.php in core/modules/migrate/src/Plugin/migrate/destination/DestinationBase.php
DrupalImageCaption.php in core/modules/ckeditor/src/Plugin/CKEditorPlugin/DrupalImageCaption.php
DrupalMedia.php in core/modules/ckeditor/src/Plugin/CKEditorPlugin/DrupalMedia.php
EditorBase.php in core/modules/editor/src/Plugin/EditorBase.php
ExecutablePluginBase.php in core/lib/Drupal/Core/Executable/ExecutablePluginBase.php
FieldPluginBase.php in core/modules/migrate_drupal/src/Plugin/migrate/field/FieldPluginBase.php
FilterBase.php in core/modules/filter/src/Plugin/FilterBase.php
HelpSectionPluginBase.php in core/modules/help/src/Plugin/HelpSection/HelpSectionPluginBase.php
HelpTopicPluginBase.php in core/modules/help_topics/src/HelpTopicPluginBase.php
ImageEffectBase.php in core/modules/image/src/ImageEffectBase.php
ImageToolkitBase.php in core/lib/Drupal/Core/ImageToolkit/ImageToolkitBase.php
ImageToolkitOperationBase.php in core/lib/Drupal/Core/ImageToolkit/ImageToolkitOperationBase.php
InPlaceEditorBase.php in core/modules/quickedit/src/Plugin/InPlaceEditorBase.php
JoinPluginBase.php in core/modules/views/src/Plugin/views/join/JoinPluginBase.php
LayoutDefault.php in core/lib/Drupal/Core/Layout/LayoutDefault.php
LinkRelationType.php in core/lib/Drupal/Core/Http/LinkRelationType.php
MediaSourceBase.php in core/modules/media/src/MediaSourceBase.php
MenuLinkBase.php in core/lib/Drupal/Core/Menu/MenuLinkBase.php
Migration.php in core/modules/migrate/src/Plugin/Migration.php
MockComplexContextBlock.php in core/modules/system/tests/modules/plugin_test/src/Plugin/plugin_test/mock_block/MockComplexContextBlock.php
MockUserNameBlock.php in core/modules/system/tests/modules/plugin_test/src/Plugin/plugin_test/mock_block/MockUserNameBlock.php
NullIdMap.php in core/modules/migrate/src/Plugin/migrate/id_map/NullIdMap.php
PluginBase.php in core/modules/views/src/Plugin/views/PluginBase.php
PluginSettingsBase.php in core/lib/Drupal/Core/Field/PluginSettingsBase.php
ProcessPluginBase.php in core/modules/migrate/src/ProcessPluginBase.php
RenderElement.php in core/lib/Drupal/Core/Render/Element/RenderElement.php
ResourceBase.php in core/modules/rest/src/Plugin/ResourceBase.php
SearchPluginBase.php in core/modules/search/src/Plugin/SearchPluginBase.php
SectionStorageBase.php in core/modules/layout_builder/src/Plugin/SectionStorage/SectionStorageBase.php
SelectionPluginBase.php in core/lib/Drupal/Core/Entity/EntityReferenceSelection/SelectionPluginBase.php
SimpleConfigSectionStorage.php in core/modules/layout_builder/tests/modules/layout_builder_test/src/Plugin/SectionStorage/SimpleConfigSectionStorage.php
SourcePluginBase.php in core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php
Sql.php in core/modules/migrate/src/Plugin/migrate/id_map/Sql.php
TipPluginBase.php in core/modules/tour/src/TipPluginBase.php
TypedDataStringBlock.php in core/modules/system/tests/modules/plugin_test/src/Plugin/plugin_test/mock_block/TypedDataStringBlock.php
VariantBase.php in core/lib/Drupal/Core/Display/VariantBase.php

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