private Request setNodeState(String node, String newNodeState, Target connection) {
        Request req = new Request("setNodeState");
        req.parameters().add(new StringValue(node));
        req.parameters().add(new StringValue(newNodeState));
        connection.invokeSync(req, timeout());
        return req;
    }
Note: RpcServer is only used in unit tests

@author humbe
clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/RpcServerTest.java