public IEnumerable<DepartmentEmployeeHistoryViewModel> GetEmployeeDepartmentHistory(int employeeId)
 {
     var request = new GetEmployeeDepartmentHistoryRequest(employeeId);
         var response = this.employeeService.GetDepartmentHistory(request);
         if (response != null && response.Exception == null)
         {
             return response.DepartmentHistory.ToList();
         }
     return null;
 }
        public GetEmployeeDepartmentHistoryResponse GetDepartmentHistory(
            GetEmployeeDepartmentHistoryRequest getEmployeeDepartmentHistoryRequest)
        {
            var response = new GetEmployeeDepartmentHistoryResponse();

            var departmentEmployees =
                this.departmentEmployeeRepository.GetDepartmentEmployeeHistory(getEmployeeDepartmentHistoryRequest.Id);

            if (departmentEmployees != null)
            {
                response.DepartmentHistory = departmentEmployees.ConvertToViewModels(this.GetDepartmentNameDictionary());
            }
            else
            {
                response.Exception = this.GetGenericResourceNotFoundException();
            }
            return response;
        }