Contao\Widget::getEmptyValue PHP Method

    public function getEmptyValue()
    {
        if (!isset($GLOBALS['TL_DCA'][$this->strTable]['fields'][$this->strField]['sql'])) {
            return '';
        }
        return static::getEmptyValueByFieldType($GLOBALS['TL_DCA'][$this->strTable]['fields'][$this->strField]['sql']);
    }