trait viewElementsTrait in Fasttoggle 8.2

trait viewElementsTrait {

  /**
   * {@inheritdoc}
   */
  public function viewElements(FieldItemListInterface $items, $langcode) {

    // Get the elements without Fasttoggle links applied.
    $elements = parent::viewElements($items, $langcode);
    $parent = $items
      ->getParent()
      ->getValue();
    $object_type = $parent
      ->getEntityTypeId();
    $object_id = $parent
      ->id();
    $controller = new FasttoggleController();
    $objectManager = $controller
      ->getObjectManager($parent);
    if (!$objectManager) {
      return $elements;
    }

    // Calculate an access result and add cache tags to $elements.
    $accessible = $objectManager
      ->mayEditEntity();
    if ($accessible
      ->isForbidden()) {
      return $elements;
    }
    $renderer = \Drupal::service('renderer');
    $renderer
      ->addCacheableDependency($elements, $accessible);
    foreach ($items as $delta => $item) {
      $linkText = $elements[$delta]['#markup'];

      // Get the group & setting and check access.
      $instance = $item
        ->getFieldDefinition();
      list($groupPlugin, $settingPlugin) = $controller
        ->groupAndSettingFromFieldName($instance);
      if (!$groupPlugin || !$settingPlugin) {
        $this
          ->messenger()
          ->addError("Fasttoggle plugin definition for '{$instance->getName()}' field not found.", "error");
        continue;
      }
      $settingPlugin
        ->setObject($parent);
      if (!$settingPlugin
        ->mayEdit()
        ->isAllowed()) {
        continue;
      }
      $cid = Crypt::randomBytesBase64();
      $group = $groupPlugin
        ->getPluginId();
      $setting = $settingPlugin
        ->getPluginId();

      // Cache using the token generated as the key.
      $cached_fieldview_config = [
        'object_type' => $object_type,
        'object_id' => $object_id,
        'group' => $group,
        'setting' => $setting,
        'token' => $cid,
        'plugin_definition' => $items
          ->getPluginDefinition(),
        'field_definition' => $items
          ->getFieldDefinition(),
        'formatter_settings' => [
          'format' => $this
            ->getSetting('format'),
          'format_custom_true' => $this
            ->getSetting('format_custom_true'),
          'format_custom_false' => $this
            ->getSetting('format_custom_false'),
        ],
        'label' => $this->label,
        'view_mode' => $this->viewMode,
        'third_party_settings' => $this->thirdPartySettings,
        'langcode' => $langcode,
      ];
      \Drupal::cache()
        ->set('fasttoggle-' . $cid, $cached_fieldview_config, Cache::PERMANENT, [
        'fasttoggle',
        "{$object_type}_{$object_id}",
      ]);
      $url_args = [
        'token' => $cid,
      ];
      $elements[$delta] = $settingPlugin
        ->render_array($cid, $linkText, $url_args);
    }
    return $elements;
  }

}