public function fromSqlToIso8601Time(string $string, ?DateTimeZone $displayedTimeZone = null): string
    {
        $dateTime = DateTime::createFromFormat(
            "Y-m-d H:i:s",
            $string,
            $displayedTimeZone
        );

        if ($dateTime === false) {
            return "";
        }

        return $dateTime->format(DateTime::ATOM);
    }