public void setNodeState(NodeState state, String hostInfo) {
        log.log(Level.FINE, () -> "Dummy node " + this + " got new state: " + state);
        synchronized(timer) {
            this.nodeState = state;
            this.hostInfo = hostInfo;
            replyToPendingNodeStateRequests();
        }
    }
Returns the latest system state version received, or empty if none are received yet.
clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/DummyVdsNode.java