public function setIsUpselling(string $is_upselling = "F") : CNabuDataObject
    {
        if ($is_upselling === null) {
            throw new ENabuCoreException(
                    ENabuCoreException::ERROR_NULL_VALUE_NOT_ALLOWED_IN,
                    array("\$is_upselling")
            );
        }
        $this->setValue('nb_commerce_product_is_upselling', $is_upselling);
        
        return $this;
    }