code: private static DateFormat getDateFormat() {
          SimpleDateFormat dateFormat = new SimpleDateFormat(DATE_FORMAT_STRING);
          dateFormat.setTimeZone(UTC);
          return dateFormat;
      }
docs: Return a date format object for writing and parsing dates to JSON.
  <p>
  This method always creates a new instance because DateFormats are not thread safe.
  
  @return a date format for reading and writing JSON dates