SearchIndexingInterface

class \Drupal\help\Plugin\Search\HelpSearch extends \Drupal\search\Plugin\SearchPluginBase implements \Drupal\Core\Access\AccessibleInterface, \Drupal\search\Plugin\SearchIndexingInterface
class \Drupal\node\Plugin\Search\NodeSearch extends \Drupal\search\Plugin\ConfigurableSearchPluginBase implements \Drupal\Core\Access\AccessibleInterface, \Drupal\search\Plugin\SearchIndexingInterface, \Drupal\Core\Security\TrustedCallbackInterface