@Override
    public String getCode() {
        return "http://jabber.org/protocol/admin#announce";
    }
Sends a message to all online users

@author Guus der Kinderen, guus@goodbytes.nl
@see <a href="https://xmpp.org/extensions/xep-0133.html#announce">XEP-0133 Send Announcement to Online Users</a>
xmppserver/src/main/java/org/jivesoftware/openfire/commands/admin/SendAnnouncementToOnlineUsers.java