public String countryCode() {
        return countryCode;
    }
REQUIRED
The [two-character ISO 3166-1 code](/docs/integration/direct/rest/country-codes/) that identifies the country or region.<blockquote><strong>Note:</strong> The country code for Great Britain is <code>GB</code> and not <code>UK</code> as used in the top-level domain names for that country. Use the `C2` country code for China worldwide for comparable uncontrolled price (CUP) method, bank card, and cross-border transactions.</blockquote>
pay-java-paypal/src/main/java/com/egzosn/pay/paypal/v2/bean/order/AddressPortable.java