FallbackPluginManagerInterface.php

<?php

namespace Drupal\Component\Plugin;

/**
 * An interface implemented by plugin managers with fallback plugin behaviors.
 */
interface FallbackPluginManagerInterface {

  /**
   * Gets a fallback id for a missing plugin.
   *
   * @param string $plugin_id
   *   The ID of the missing requested plugin.
   * @param array $configuration
   *   An array of configuration relevant to the plugin instance.
   *
   * @return string
   *   The id of an existing plugin to use when the plugin does not exist.
   */
  public function getFallbackPluginId($plugin_id, array $configuration = array());

}