public function getCompatibleTimezones()
    {
        $validTimezones = [];
        foreach ($this->dateHelper->getTimezones() as $timezoneID => $timezoneName) {
            if ($this->getDeltaTimezone($timezoneID) === null) {
                $validTimezones[$timezoneID] = $timezoneName;
            }
        }

        return $validTimezones;
    }