public static function getAutoStampColumns()
    {
        $auto_stamp = [];
        if (!empty(static::STAMP_COLUMNS)) {
            $stamp_columns = self::normalizeColumnList(static::STAMP_COLUMNS);
            $auto_stamp = array_filter($stamp_columns, function ($mode) {
                return $mode === 'auto';
            });
        }
        return array_keys($auto_stamp);
    }