public function GetRequiredFields()
    {
        $aRequiredFields = parent::GetRequiredFields();
        if ($this->fieldIsDhlPackstation) {
            $aRequiredFields[] = 'address_additional_info';
            $sKey = array_search('telefon', $aRequiredFields);
            if (false !== $sKey) {
                unset($aRequiredFields[$sKey]);
            }
            $sKey = array_search('fax', $aRequiredFields);
            if (false !== $sKey) {
                unset($aRequiredFields[$sKey]);
            }
        }

        return $aRequiredFields;
    }