code: @Deprecated
      public static String getRegionForSupplementalData(
                              ULocale locale, boolean inferRegion) {
          String region = locale.getKeywordValue("rg");
          if (region != null && region.length() == 6) {
              String regionUpper = AsciiUtil.toUpperString(region);
              if (regionUpper.endsWith("ZZZZ")) {
              	return regionUpper.substring(0,2);
              }
          }
          region = locale.getCountry();
          if (region.length() == 0 && inferRegion) {
              ULocale maximized = addLikelySubtags(locale);
              region = maximized.getCountry();
          }
          return region;
      }
docs: <strong>[icu]</strong> Get the region to use for supplemental data lookup.
  Uses
  (1) any region specified by locale tag "rg"; if none then
  (2) any unicode_region_tag in the locale ID; if none then
  (3) if inferRegion is TRUE, the region suggested by
  getLikelySubtags on the localeID.
  If no region is found, returns empty string ""
  
  @param locale
  The locale (includes any keywords) from which
  to get the region to use for supplemental data.
  @param inferRegion
  If TRUE, will try to infer region from other
  locale elements if not found any other way.
  @return
  String with region to use ("" if none found).
  @deprecated This API is ICU internal only.
  @hide draft / provisional / internal are hidden on Android