code: public Date getExpiry() {
          String dateTime = getFieldValue(SubscribeOptionFields.expire);
          try {
              return XmppDateTime.parseDate(dateTime);
          }
          catch (ParseException e) {
              UnknownFormatConversionException exc = new UnknownFormatConversionException(dateTime);
              exc.initCause(e);
              throw exc;
          }
      }
docs: Get the time at which the leased subscription will expire, or has expired.
  
  @return The expiry date