class SelectionBroken

SelectionPluginManager.php in drupal/core/modules/entity_reference/lib/Drupal/entity_reference/Plugin/Type/SelectionPluginManager.php

Contains \Drupal\entity_reference\Plugin\Type\SelectionPluginManager.

class SelectionBroken implements SelectionInterface {

  /**
   * Constructs a SelectionBroken object.
   */
  public function __construct($field, $instance = NULL) {
    $this->field = $field;
    $this->instance = $instance;
  }

  /**
   * Implements SelectionInterface::settingsForm().
   */
  public static function settingsForm(&$field, &$instance) {
    $form['selection_handler'] = array(
      '#markup' => t('The selected selection handler is broken.'),
    );
    return $form;
  }

  /**
   * Implements SelectionInterface::getReferencableEntities().
   */
  public function getReferencableEntities($match = NULL, $match_operator = 'CONTAINS', $limit = 0) {
    return array();
  }

  /**
   * Implements SelectionInterface::countReferencableEntities().
   */
  public function countReferencableEntities($match = NULL, $match_operator = 'CONTAINS') {
    return 0;
  }

  /**
   * Implements SelectionInterface::validateReferencableEntities().
   */
  public function validateReferencableEntities(array $ids) {
    return array();
  }

  /**
   * Implements SelectionInterface::validateAutocompleteInput().
   */
  public function validateAutocompleteInput($input, &$element, &$form_state, $form, $strict = TRUE) {
  }

  /**
   * Implements SelectionInterface::entityQueryAlter().
   */
  public function entityQueryAlter(SelectInterface $query) {
  }

}