@Override
    public void joinedCluster(byte[] nodeID) {
        // Another node joined a cluster that we're already part of. It is expected that
        // the implementation of #joinedCluster() as executed on the cluster node that just
        // joined will synchronize all relevant data. This method need not do anything.
    }
Verifies that {@link #usersSessionsCache} and {@link #usersCache} are in a consistent state.

Note that this operation can be costly in terms of resource usage. Use with caution in large / busy systems.

The returned multi-map can contain up to four keys: info, fail, pass, data. All entry values are a human readable
description of a checked characteristic. When the state is consistent, no 'fail' entries will be returned.

@return A consistency state report.
@see #usersSessionsCache which tracks user sessions.
@see #usersCache which the cache that is used tho share data with other cluster nodes.
xmppserver/src/main/java/org/jivesoftware/openfire/spi/RoutingTableImpl.java