public virtual void AddExpenseItem(Expense expense)
 {
     if (!CashTransferDocumentExpenseItems.Any(x => x.Expense.Id == expense.Id))
     {
         var newItem = new ExpenseCashTransferedItem {
             Expense  = expense,
             Document = this
         };
         ObservableCashTransferDocumentExpenseItems.Add(newItem);
         newItem.Expense.TransferedBy = newItem;
     }
 }
 public virtual void DeleteTransferedExpenses(IEnumerable <ExpenseCashTransferedItem> deletedItems)
 {
     if (deletedItems == null)
     {
         return;
     }
     foreach (ExpenseCashTransferedItem item in deletedItems)
     {
         if (ObservableCashTransferDocumentExpenseItems.Contains(item))
         {
             ObservableCashTransferDocumentExpenseItems.Remove(item);
         }
     }
 }