public JsonResult ValidateUniqueFullName(string first, string lastName, long?id)
        {
            var viewModel = new EmployeeVM
            {
                First    = first,
                LastName = lastName,
                Id       = id ?? 0
            };

            var employee = Map(viewModel);
            var result   = _employeeValidator.ValidateNames(employee);

            return(JsonValidationResult(result));
        }