FallbackPluginManagerInterface

class \Drupal\Core\Block\BlockManager extends \Drupal\Core\Plugin\DefaultPluginManager implements \Drupal\Core\Block\BlockManagerInterface, \Drupal\Component\Plugin\FallbackPluginManagerInterface uses \Drupal\Core\Plugin\CategorizingPluginManagerTrait, \Drupal\Core\Plugin\FilteredPluginManagerTrait
class \Drupal\Core\Entity\EntityReferenceSelection\SelectionPluginManager extends \Drupal\Core\Plugin\DefaultPluginManager implements \Drupal\Core\Entity\EntityReferenceSelection\SelectionPluginManagerInterface, \Drupal\Component\Plugin\FallbackPluginManagerInterface
class \Drupal\Tests\Component\Plugin\StubFallbackPluginManager extends \Drupal\Component\Plugin\PluginManagerBase implements \Drupal\Component\Plugin\FallbackPluginManagerInterface
class \Drupal\filter\FilterPluginManager extends \Drupal\Core\Plugin\DefaultPluginManager implements \Drupal\Component\Plugin\FallbackPluginManagerInterface
class \Drupal\views\Plugin\ViewsHandlerManager extends \Drupal\Core\Plugin\DefaultPluginManager implements \Drupal\Component\Plugin\FallbackPluginManagerInterface

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