code: public DateTimeFormatter withLocale(Locale locale) {
          if (locale == getLocale() || (locale != null && locale.equals(getLocale()))) {
              return this;
          }
          return new DateTimeFormatter(iPrinter, iParser, locale,
                  iOffsetParsed, iChrono, iZone, iPivotYear, iDefaultYear);
      }
docs: Returns a new formatter with a different locale that will be used
  for printing and parsing.
  <p>
  A DateTimeFormatter is immutable, so a new instance is returned,
  and the original is unaltered and still usable.
  
  @param locale the locale to use; if null, formatter uses default locale
  at invocation time
  @return the new formatter