ShipmentItem::getNeedReserveQuantity

public function getNeedReserveQuantity()
{
	if (!$this->needReserve())
	{
		return 0;
	}

	$changedFields = $this->fields->getChangedValues();
	$originalFields = $this->fields->getOriginalValues();

	return $changedFields['RESERVED_QUANTITY'] - $originalFields['RESERVED_QUANTITY'];
}