Product::normalizeDiscountForPercentage

static function normalizeDiscountForPercentage(ProductRow $product): void
{
	if (is_null($product->getDiscountRate()))
	{
		self::addErrorForProduct(
			new Error(
			"Discount Rate (DISCOUNT_RATE) is required if Percentage Discount Type (DISCOUNT_TYPE_ID) is used. ID = {$product->getId()}"
			),
			$product
		);
		return;
	}

	if (is_null($product->getDiscountSum()))
	{
		$discountSum = Discount::calculateDiscountSum($product->getPriceExclusive(), $product->getDiscountRate());
		$product->setDiscountSum($discountSum);
	}
}