/**
  * Returns the plugin ID for a given toolkit and operation.
  *
  * @param \Drupal\Core\ImageToolkit\ImageToolkitInterface $toolkit
  *   The toolkit instance.
  * @param string $operation
  *   The operation (e.g. "crop").
  *
  * @return string
  *   The plugin ID.
  *
  * @throws \Drupal\Component\Plugin\Exception\PluginNotFoundException
  *   When no plugin is available.
  */
 protected function getToolkitOperationPluginId(ImageToolkitInterface $toolkit, $operation)
 {
     $toolkit_id = $toolkit->getPluginId();
     $definitions = $this->getDefinitions();
     $definitions = array_filter($definitions, function ($definition) use($toolkit_id, $operation) {
         return $definition['toolkit'] == $toolkit_id && $definition['operation'] == $operation;
     });
     if (!$definitions) {
         // If this image toolkit plugin is a derivative and returns no operation,
         // try once again with its base plugin.
         $base_toolkit_id = $toolkit->getBaseId();
         if ($toolkit_id != $base_toolkit_id && !empty($base_toolkit_id)) {
             $base_toolkit = $this->toolkitManager->createInstance($base_toolkit_id);
             return $this->getToolkitOperationPluginId($base_toolkit, $operation);
         }
         $message = SafeMarkup::format("No image operation plugin for '@toolkit' toolkit and '@operation' operation.", array('@toolkit' => $toolkit_id, '@operation' => $operation));
         throw new PluginNotFoundException($toolkit_id . '.' . $operation, $message);
     } else {
         // Pickup the first plugin found.
         // @todo In https://www.drupal.org/node/2110591 we'll return here the UI
         //   selected plugin or the first found if missed.
         $definition = reset($definitions);
         return $definition['id'];
     }
 }
 /**
  * {@inheritdoc}
  */
 public function getToolkitOperation(ImageToolkitInterface $toolkit, $operation)
 {
     $plugin_id = $this->getToolkitOperationPluginId($toolkit->getPluginId(), $operation);
     return $this->createInstance($plugin_id, array(), $toolkit);
 }