@Override
    public void onOutput(OutputEvent event) {
        if (event instanceof ProgressStartEvent) {
            ProgressStartEvent startEvent = (ProgressStartEvent) event;
            if (startEvent.isBuildOperationStart()) {
                if (buildStartTimestamp == 0 && startEvent.getParentProgressOperationId() == null) {
                    // The very first event starts the Initializing phase