@Override
    public void joinedCluster() {
        // The local node joined a cluster.
        //
        // Upon joining a cluster, clustered caches are reset to their clustered equivalent (by the swap from the local
        // cache implementation to the clustered cache implementation that's done in the implementation of
        // org.jivesoftware.util.cache.CacheFactory.joinedCluster). This means that they now hold data that's
        // available on all other cluster nodes. Data that's available on the local node needs to be added again.
        restoreCacheContent();

        // It does not appear to be needed to invoke any kind of event listeners for the data that was gained by joining
        // the cluster (eg: new server features provided by other cluster nodes now available to the local cluster node):
        // the only cache that's being used in this implementation does not have an associated event listening mechanism
        // when data is added to or removed from it.
    }
Removes a feature from the information returned whenever a disco for information is
made against the server.

@param namespace the namespace of the feature to be removed.
xmppserver/src/main/java/org/jivesoftware/openfire/disco/IQDiscoInfoHandler.java