public string CreateStandingOrder(StandingOrderEntityData requestData)
        {
            EnsureRepositoryOpen("CreateStandingOrder");

            var standingOrder = new StandingOrderEntityImp();
            SetRequestEntityImpData(standingOrder, requestData);
            _allStandingOrders.Add(standingOrder);
            _persistenceHandler.SaveChanges(new SavingTask(FilePath, standingOrder.Clone()));

            return standingOrder.PersistentId;
        }