public void RegisterEmailValidator(params IValidator <UserAccount>[] items)
 {
     emailValidators.AddRange(items);
 }
 public void RegisterUsernameValidator(params IValidator <UserAccount>[] items)
 {
     usernameValidators.AddRange(items);
 }
 public void RegisterPasswordValidator(params IValidator <UserAccount>[] items)
 {
     passwordValidators.AddRange(items);
 }
 public void RegisterPhoneNumberValidator(params IValidator <UserAccount>[] items)
 {
     phoneNumberValidators.AddRange(items);
 }