@Override
    public void writeExternal(ObjectOutput out) throws IOException {
        ExternalizableUtil.getInstance().writeByteArray(out, nodeID.toByteArray());
        ExternalizableUtil.getInstance().writeBoolean(out, available);
    }
Internal object used by RoutingTableImpl to keep track of the node that own a ClientSession
and whether the session is available or not.

@author Gaston Dombiak
xmppserver/src/main/java/org/jivesoftware/openfire/spi/ClientRoute.java