public synchronized boolean isRejected() {
            return joinResult != null && !joinResult;
        }
Retrieve and clean the list of stanzas that have been queued after federation was initiated, but before it
was finished.

@return A list of queued stanzas (possibly empty).
xmppserver/src/main/java/org/jivesoftware/openfire/muc/spi/FMUCHandler.java