Change title/subtitle chart in DrillDown and DrillUp

Hi. I expect someone could help me.

I have created a multilevel drilldown chart following this topic:
https://github.com/vaadin/charts/blob/master/examples/src/main/java/com/vaadin/addon/charts/examples/columnandbar/ColumnWithNativeLazyDrilldownByIndex.java

I've modified this code to add a superlevel of "Browser brands" serie. The new structure of drilldown chart is next:

1. Year 2015
1. MSIE
1. MSIE 4.0
2. MSIE 5.0
2. Firefox
1. Firefox 1.0
2. Firefox 1.5
2. Year 2016
1. MSIE
1. MSIE 6.0
2. MSIE 7.0
3. MSIE 8.0
4. MSIE 9.0
2. Firefox
1. Firefox 2.0
2. Firefox 3.0

It works fine, but what I want is to change the title or subtitle of the chart in order to follow the path of charts (like breadcrumbs in web pages). For example, if I'm watching a chart where all 2016-MSIE are shown (MSIE 6.0, 7.0, 8.0), I would like to see in subtitle chart this text:
"You are in: Year 2016 > MSIE" but if I return to Year 2016 chart, the text should change to: "You are in: Year 2016".

With this code:
 

List<String> breadcrumb = new ArrayList<String>();

chart.setDrilldownCallback(new DrilldownCallback() {
    @Override
    public Series handleDrilldown(DrilldownEvent event) {
        Series ss = getPointDrilldown(event.getItemIndex());
        conf.setSubTitle(ss.getName());
        breadcrumb.add(ss.getName());
        chart.drawChart();
        return ss ;
    }
});

chart.addChartDrillupListener(new ChartDrillupListener() {

            @Override
            public void onDrillup(ChartDrillupEvent event) {
                String subtitle = breadcrumb.get(breadcrumb.size() - 2);
                breadcrumb.remove(breadcrumb.size() - 1);
                conf.setSubTitle(subtitle);
                chart.drawChart();
            }
        });

I get subtitle changes when drilldown, but in leaf level, when I click DrillupButton, the navigation changes to the first chart directly, where years 2015-2016 appears. If I remove all chart.drawChart() methods, the navigations works fine but subtitle doesn't change.

What I would like to know is if there is a method like refresh() or similar way to get change subtitle with a correct navigation of charts. I have proved with chart.MarkasDirty(), but it doesn't work.

Thanks for all. Best regards.

AlfaGavi