public IEnumerable <ModelValidationResult> Validate() { var balanceResult = Balance.ValidateMoney(nameof(Balance)); if (balanceResult != null) { yield return(balanceResult); } var dateResult = CreationDate.ValidateDateTime(nameof(CreationDate)); if (dateResult != null) { yield return(dateResult); } var accountTypeResult = AccountType.ValidateAccountType(nameof(AccountType)); if (accountTypeResult != null) { yield return(accountTypeResult); } }