public virtual void AddIncomeItem(Income income)
 {
     if (!CashTransferDocumentIncomeItems.Any(x => x.Income.Id == income.Id))
     {
         var newItem = new IncomeCashTransferedItem {
             Income   = income,
             Document = this
         };
         ObservableCashTransferDocumentIncomeItems.Add(newItem);
         newItem.Income.TransferedBy = newItem;
     }
 }
 public virtual void DeleteTransferedIncomes(IEnumerable <IncomeCashTransferedItem> deletedItems)
 {
     if (deletedItems == null)
     {
         return;
     }
     foreach (IncomeCashTransferedItem item in deletedItems)
     {
         if (ObservableCashTransferDocumentIncomeItems.Contains(item))
         {
             ObservableCashTransferDocumentIncomeItems.Remove(item);
         }
     }
 }