code: public static String format(final long millis, final String pattern, final TimeZone timeZone, final Locale locale) {
          return format(new Date(millis), pattern, timeZone, locale);
      }
docs: <p>Formats a date/time into a specific pattern in a time zone  and locale.</p>
  
  @param millis  the date to format expressed in milliseconds
  @param pattern  the pattern to use to format the date, not null
  @param timeZone  the time zone  to use, may be <code>null</code>
  @param locale  the locale to use, may be <code>null</code>
  @return the formatted date