code: public static String getDateAsIso8601(Date date) {
  
          synchronized (CmsSearchUtil.class) {
              if (DATEFORMAT_ISO_8601.getTimeZone() != TIMEZONE_UTC) {
                  DATEFORMAT_ISO_8601.setTimeZone(TIMEZONE_UTC);
              }
              return DATEFORMAT_ISO_8601.format(date);
          }
      }
docs: Returns a given date object in the ISO 8601 format.
  
  @param date that should be converted.
  @return string that represents the given date in the ISO 8601 format.