private function transformSnapshotTimestamps(array $data)
    {
        foreach (['createTime', 'updateTime', 'readTime'] as $timestampField) {
            if (!isset($data[$timestampField])) {
                continue;
            }

            list ($dt, $nanos) = $this->parseTimeString($data[$timestampField]);

            $data[$timestampField] = new Timestamp($dt, $nanos);
        }

        return $data;
    }