code: public static ULocale addLikelySubtags(ULocale loc) {
          String[] tags = new String[3];
          String trailing = null;
  
          int trailingIndex = parseTagString(
                  loc.localeID,
                  tags);
  
          if (trailingIndex < loc.localeID.length()) {
              trailing = loc.localeID.substring(trailingIndex);
          }
  
          String newLocaleID =
                  createLikelySubtagsString(
                          tags[0],
                          tags[1],
                          tags[2],
                          trailing);
  
          return newLocaleID == null ? loc : new ULocale(newLocaleID);
      }
docs: <strong>[icu]</strong> Adds the likely subtags for a provided locale ID, per the algorithm
  described in the following CLDR technical report:
  
  http://www.unicode.org/reports/tr35/#Likely_Subtags
  
  If the provided ULocale instance is already in the maximal form, or there is no
  data available available for maximization, it will be returned.  For example,
  "und-Zzzz" cannot be maximized, since there is no reasonable maximization.
  Otherwise, a new ULocale instance with the maximal form is returned.
  
  Examples:
  
  "en" maximizes to "en_Latn_US"
  
  "de" maximizes to "de_Latn_US"
  
  "sr" maximizes to "sr_Cyrl_RS"
  
  "sh" maximizes to "sr_Latn_RS" (Note this will not reverse.)
  
  "zh_Hani" maximizes to "zh_Hans_CN" (Note this will not reverse.)
  
  @param loc The ULocale to maximize
  @return The maximized ULocale instance.