public void setCountryCode(String countryCode)
    {
        countryCode = countryCode.trim().toUpperCase();

        if ( countryCode.isEmpty() ) {
            throw new RuntimeException( "'country code' should not be empty" );
        }

        if ( this.countryISOCodes.indexOf( countryCode ) < 0 ) {
            throw new RuntimeException( "'country code' should be one of ISO-3166-2" );
        }

        this.countryCode = countryCode;
    }