code: public static String getDateAsIso8601(long date) {
  
          // Check if date is set
          if ((date > Long.MIN_VALUE) && (date < Long.MAX_VALUE)) {
              final Date d_date = new Date(date);
              return getDateAsIso8601(d_date);
          }
          return null;
      }
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.