code: @Nonnull
    public ETriState isValidPostalCode (@Nullable final Locale aCountry, @Nullable final String sPostalCode)
    {
      final IPostalCodeCountry aPostalCountry = getPostalCountryOfCountry (aCountry);
      if (aPostalCountry == null)
        return ETriState.UNDEFINED;
      return ETriState.valueOf (aPostalCountry.isValidPostalCode (sPostalCode));
    }
docs: Check if the passed postal code is valid for the passed country.
  
  @param aCountry
  The country to check. May be <code>null</code>.
  @param sPostalCode
  The postal code to check. May be <code>null</code>.
  @return {@link ETriState#UNDEFINED} if no information for the passed
  country are present, {@link ETriState#TRUE} if the postal code is
  valid or {@link ETriState#FALSE} if the passed postal code is
  explicitly not valid for the passed country.