code: public void setTimeZoneFormat(TimeZoneFormat tzfmt) {
          if (tzfmt.isFrozen()) {
              // If frozen, use it as is.
              tzFormat = tzfmt;
          } else {
              // If not frozen, clone and freeze.
              tzFormat = tzfmt.cloneAsThawed().freeze();
          }
      }
docs: <strong>[icu]</strong> Allows you to set the time zone formatter.
  
  @param tzfmt the new time zone formatter