How to find a room

jicofo receive a message like this:

<message to="focus.meet.jitsi" from="we4_61i2ne-legw9@meet.jitsi/0nofbK9b"> <body>{"event":"aaaaa"}</body> </message>

I use this code. I can get a fromJid,but I don’t konw how to find a room with “we4_61i2ne-legw9@meet.jitsi/0nofbK9b” ?
Jid fromJid = JidCreate.from(“we4_61i2ne-legw9@meet.jitsi/0nofbK9b”);