public User createUser(User toSave)
        {
            if (_repo.getUserFromDatabase(toSave.citizenServiceNumber) != null)
            {
                return(null);
            }

            toSave.password = generatePassword(toSave.password);
            RegistrationModel model = new RegistrationModel
            {
                LastName             = toSave.lastName,
                CitizenServiceNumber = toSave.citizenServiceNumber,
                FirstName            = toSave.firstName
            };
            HttpResponseMessage response = RestHelper.AasHttpClient()
                                           .PostAsync($"owners", RestHelper.ConvertToSendableHttpObject(model)).Result;

            response.EnsureSuccessStatusCode();
            string        msg = response.Content.ReadAsStringAsync().Result;
            RestUserModel mod = JsonConvert.DeserializeObject <RestUserModel>(msg);

            toSave.address  = mod.Address;
            toSave.birthDay = DateTime.ParseExact(mod.Birthday, "dd-MM-yyyy",
                                                  System.Globalization.CultureInfo.InvariantCulture);
            toSave.cars         = _carService.GetCarsOfUserFromAAS(toSave.citizenServiceNumber) as List <Car>;
            toSave.Language     = "NLD";
            toSave.lastSyncTime = DateTime.Now;
            toSave.invoices     = new List <Invoice>();
            return(_repo.Add(toSave));
        }