ToDictionary3

 public void ReloadCache(TransactionArgs transactionArgs = null)
        {
            List<ATMTaskTypePriorityEntry> taskTypePriorityEntries = _taskTypePriorityDatabaseAccess.GetAllPriorities(transactionArgs);
            TaskTypePriorities = ConvertTableEntriesToTaskTypePriorities(taskTypePriorityEntries);
        }

        private List<ATMTaskTypePriorities> ConvertTableEntriesToTaskTypePriorities(List<ATMTaskTypePriorityEntry> taskTypePriorityEntries)
        {
            List<IGrouping<long, ATMTaskTypePriorityEntry>> entriesByTaskTypeId = taskTypePriorityEntries.GroupBy(entry => entry.TaskTypeDbId).ToList(); //group entries by TaskTypeDbId
            List<ATMTaskTypePriorities> prioritiesList = new List<ATMTaskTypePriorities>(entriesByTaskTypeId.Count); //we know how long should list be, so initialize it accordingly
            foreach (var entryGroup in entriesByTaskTypeId)
            {
                Dictionary<int, ATMTaskPriorities> taskTypePriorities = new Dictionary<int, ATMTaskPriorities>();
                foreach (var entry in entryGroup)
                    taskTypePriorities[entry.EventThreshold] = entry.Priority; //this is design decision - if entries duplicates, last will win

                prioritiesList.Add(new ATMTaskTypePriorities(entryGroup.Key, taskTypePriorities));
            }

            return prioritiesList;
        }