code: public static String toHttpDate(Date date) {
          notNull("date", date);
          return DateTimeFormatter.RFC_1123_DATE_TIME
              .withZone(ZoneOffset.UTC)
              .format(Instant.ofEpochMilli(date.getTime()));
      }
docs: Converts a date into a date string as used in HTTP headers (defined in RFC 7321), for example <code>Tue, 15 Nov 1994 08:12:31 GMT</code>
  
  @param date A date to format
  @return The date as a formatted string
  @throws IllegalArgumentException If the date is null