code: public boolean scheduleNotification(ScheduledNotification notification, List<String> message,
                                          Collection<Recipient> recipients) {
          if (notification.getIen() > 0) {
              deleteScheduledNotification(notification);
          }
  
          String extraInfo = StrUtil.fromList(Arrays.asList(notification.getExtraInfo()), StrUtil.U);
          return broker.callRPCBool("RGCWXQ SCHALR", notification.getDeliveryDate(), scheduledPrefix,
              notification.getSubject(), extraInfo, message, prepareRecipients(recipients));
      }
docs: Creates a schedule notification. If the notification is replacing an existing one, the
  existing one will be first deleted and a new one created in its place.
  
  @param notification Notification to be scheduled.
  @param message The associated message, if any.
  @param recipients The target recipients.
  @return True if the notification was successfully scheduled.