public void DemandsAdd(Demand demand) { if (demand.GetType() == typeof(ProductionOrderBom)) { _productionOrderBoms.Add((ProductionOrderBom)demand); } else if (demand.GetType() == typeof(StockExchangeDemand)) { _stockExchangeDemands.Add((StockExchangeDemand)demand); } else if (demand.GetType() == typeof(CustomerOrderPart)) { _customerOrderParts.Add((CustomerOrderPart)demand); } else { throw new MrpRunException("This type is unknown."); } }