code: public void notifications_send(Collection<Integer> recipientIds, CharSequence notification)
      throws FacebookException, IOException {
      assert (null != notification);
      ArrayList<Pair<String, CharSequence>> args = new ArrayList<Pair<String, CharSequence>>(3);
      if (null != recipientIds && !recipientIds.isEmpty()) {
        args.add(new Pair<String, CharSequence>("to_ids", delimit(recipientIds)));
      }
      args.add(new Pair<String, CharSequence>("notification", notification));
      this.callMethod(FacebookMethod.NOTIFICATIONS_SEND, args);
    }
docs: Send a notification message to the specified users on behalf of the logged-in user.
  
  @param recipientIds the user ids to which the message is to be sent. if empty,
  notification will be sent to logged-in user.
  @param notification the FBML to be displayed on the notifications page; only a stripped-down
  set of FBML tags that result in text and links is allowed
  @return a URL, possibly null, to which the user should be redirected to finalize
  the sending of the email
  @see <a href="http://wiki.developers.facebook.com/index.php/Notifications.sendEmail">
  Developers Wiki: notifications.send</a>