Expanded class hierarchy of Subquery

class \Drupal\Component\Plugin\PluginBase implements PluginInspectionInterface
- class \Drupal\field\Plugin\PluginSettingsBase implements PluginSettingsInterface
- class \Drupal\layout\Plugin\layout\layout\StaticLayout implements LayoutInterface
- class \Drupal\plugin_test\Plugin\plugin_test\mock_block\MockLayoutBlock
- class \Drupal\plugin_test\Plugin\plugin_test\mock_block\MockTestBlock
- class \Drupal\plugin_test\Plugin\plugin_test\mock_block\MockUserLoginBlock
- class \Drupal\rest\Plugin\ResourceBase
- class \Drupal\views\Plugin\views\join\JoinPluginBase
  - class \Drupal\views\Plugin\views\join\Standard
  - class \Drupal\views\Plugin\views\join\Subquery
  - class \Drupal\views_test_data\Plugin\views\join\JoinTest
- class \Drupal\views\Plugin\views\PluginBase