Setting a room subject to be null

You don’t seem to be able to set the subject of a room to be null. We send this packet:

but Openfire does nothing. I suspect it’s this code (in trunk still). Notice the check on the length of the subject.

Is there an XMPP reason to do this check?

if (packet.getSubject() != null && packet.getSubject().trim().length() > 0 &&
                                Message.Type.groupchat == packet.getType() &&
                                (packet.getBody() == null || packet.getBody().trim().length() == 0)) {
                            // An occupant is trying to change the room's subject
                            role.getChatRoom().changeSubject(packet, role);