public void setSystemStateVersionActivationAcked(Integer version, boolean success) {
        if (success && (version > clusterStateVersionActivationAcked)) {
            clusterStateVersionActivationAcked = version;
        } else if (!success) {
            clusterStateVersionActivationSent = -1; // Trigger resend
        }
    }
Sets the wanted state. The wanted state is taken as UP if a null argument is given
clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/NodeInfo.java