code: public void addCountryCode(final String countryCode) {
          if (null == countryCodes) {
              countryCodes = new ArrayList<String>();
          }
          countryCodes.add(countryCode);
      }
docs: Limit search results to a specific country (or a list of countries). &lt;countrycode&gt; should be the ISO
  3166-1alpha2 code, e.g. gb for the United Kingdom, de for Germany, etc.
  
  @param countryCode
  the country code to add