6 classes are annotated with Layout in Drupal 8

BlankLayout in core/modules/layout_builder/src/Plugin/Layout/BlankLayout.php

Provides a layout plugin that produces no output.

LayoutBuilderTestPlugin in core/modules/layout_builder/tests/modules/layout_builder_test/src/Plugin/Layout/LayoutBuilderTestPlugin.php

Plugin annotation @Layout( id = "layout_builder_test_plugin", label = @Translation("Layout Builder Test Plugin"), regions = { "main" = { "label" = @Translation("Main Region") } }, )

LayoutTestDependenciesPlugin in core/modules/system/tests/modules/layout_test/src/Plugin/Layout/LayoutTestDependenciesPlugin.php

Provides a plugin that contains config dependencies.

LayoutTestPlugin in core/modules/system/tests/modules/layout_test/src/Plugin/Layout/LayoutTestPlugin.php

The plugin that handles the default layout template.

TestLayoutContentFooter in core/modules/field_layout/tests/modules/field_layout_test/src/Plugin/Layout/TestLayoutContentFooter.php

Provides an annotated layout plugin for field_layout tests.

TestLayoutMainFooter in core/modules/field_layout/tests/modules/field_layout_test/src/Plugin/Layout/TestLayoutMainFooter.php

Provides an annotated layout plugin for field_layout tests.