public static void fireLeftCluster() {
        try {
            Log.info("Firing left cluster event for this node");
            Event event = new Event(EventType.left_cluster, null);
            events.put(event);
        } catch (InterruptedException e) {
            // Should never happen
            Log.error(e.getMessage(), e);
        }
    }
Triggers event indicating that this JVM is no longer part of the cluster. This could
happen when disabling clustering support or removing the enterprise plugin that provides
clustering support.<p>

Moreover, if we were in a "split brain" scenario (ie. separated cluster islands) and the
island were this JVM belonged was marked as "old" then all nodes of that island will
get the {@code left cluster event} and {@code joined cluster events}. That means that
caches will be reset and thus will need to be repopulated again with fresh data from this JVM.
This also includes the case where this JVM was the senior cluster member and when the islands
met again then this JVM stopped being the senior member.
xmppserver/src/main/java/org/jivesoftware/openfire/cluster/ClusterManager.java