public async Task <IActionResult> Index(string customerGroupId, string customerAccount)
        {
            var model = new IndexCustomerViewModel
            {
                CustomerGroupId = customerGroupId,
                CustomerAccount = customerAccount
            };

            if (string.IsNullOrEmpty(customerGroupId))
            {
                model.Customers = await odataService.GetCustomers();
            }
            else
            {
                model.Customers = await odataService.GetCustomersByGroup(customerGroupId);
            }

            return(View(model));
        }