I've found out that it was possible to create a room without a localpart in a JID by sending:

<iq type="set" to="muc.domain" id="1">
<query xmlns="http://jabber.org/protocol/muc#owner">
<x xmlns="jabber:x:data"/>
</query>
</iq>

where muc.domain is address of a MUC component.

Entries like that (without localpart in a JID) are invalid and caused NPE in the service discovery module.

I've fixed this issue by:

• omitting rooms without localpart in JID from discovery
• adding protection to make sure that it is not possible to create rooms like that anymore
• added code which removes rooms without localpart in JID on the service startup

Bartosz, please review my changes.

Looks good.