public function index($params = [], $optParams = [])
    {
        if ($optParams instanceof IndexParams) {
            $optParams = $optParams->toArray(true);
        }

        return $this->sendRequest([], [
            'restAction' => 'index',
            'params' => $params,
            'getParams' => $optParams,
        ], function ($response) {
            $backups = [];
            if (isset($response->data['items'])) {
                foreach ($response->data['items'] as $superbackup) {
                    $backups[] = new SuperBackup($superbackup);
                }
            }

            return new Index([
                'models' => $backups,
                'nextPageToken' => $response->data['nextPageToken'],
            ]);
        });
    }