public static Long getTimeFromDateString(String dateString) {
    try {
      SimpleDateFormat dateFormatter = new SimpleDateFormat(HTTP_DATE_FORMAT, Locale.US);
      return dateFormatter.parse(dateString).getTime();
    } catch (ParseException e) {
      logger.warn("Could not parse milliseconds from an HTTP date header ({}).", dateString);
      return null;
    }
  }
Fetch time in ms for the {@code dateString} passed in, since epoch
@param dateString the String representation of the date that needs to be parsed
@return Time in ms since epoch. Note http time is kept in Seconds so last three digits will be 000.
        Returns null if the {@code dateString} is not in the expected format or could not be parsed
ambry-api/src/main/java/com/github/ambry/rest/RestUtils.java