code: public PeriodFormatter withLocale(Locale locale) {
          if (locale == getLocale() || (locale != null && locale.equals(getLocale()))) {
              return this;
          }
          return new PeriodFormatter(iPrinter, iParser, locale, iParseType);
      }
docs: Returns a new formatter with a different locale that will be used
  for printing and parsing.
  <p>
  A PeriodFormatter is immutable, so a new instance is returned,
  and the original is unaltered and still usable.
  <p>
  A null locale indicates that no specific locale override is in use.
  
  @param locale  the locale to use
  @return the new formatter