public static synchronized void shutdown() {
        if (isClusteringStarted()) {
            Log.debug("ClusterManager: Shutting down clustered cache service.");
            CacheFactory.stopClustering();
        }
    }
Shuts down the clustering service. This method should be called when the
system is shutting down or clustering has been disabled. Failing to call
this method may temporarily impact cluster performance, as the system will
have to do extra work to recover from a non-clean shutdown.
If clustering is not enabled, this method will do nothing.
xmppserver/src/main/java/org/jivesoftware/openfire/cluster/ClusterManager.java