private String toString(History.Event.Type nodeEventType) {
        return switch (nodeEventType) {
            case provisioned -> "provisioned";
            case deprovisioned -> "deprovisioned";
            case readied -> "readied";
            case reserved -> "reserved";
            case activated -> "activated";
            case wantToRetire -> "wantToRetire";
            case wantToFail -> "wantToFail";
            case retired -> "retired";
            case deactivated -> "deactivated";
            case parked -> "parked";
            case failed -> "failed";
            case deallocated -> "deallocated";
            case down -> "down";
            case up -> "up";
            case suspended -> "suspended";
            case resumed -> "resumed";
            case resized -> "resized";
            case rebooted -> "rebooted";
            case osUpgraded -> "osUpgraded";
            case firmwareVerified -> "firmwareVerified";
            case breakfixed -> "breakfixed";
            case preferToRetire -> "preferToRetire";
        };
    }
Returns the event type, or null if this event type should be ignored
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/persistence/NodeSerializer.java