Vaadin charts, how to extend Chart class

Hi,

I would like to extend the Chart class with the new class PieChart. My constructor looks like this:

public PieChart(ChartType type,Configuration conf, ContainerDataSeries series){

    super(ChartType.PIE);
    this.setHeight("500px");
    this.setWidth("500px");
    conf.addSeries(series);
    this.setConfiguration(conf);        
}

However, for some reason the superclass constructor does not really do what i thought it would do: setting the type to ChartType.Pie. I just get a default line chart. Am I missing something?
The instantiation looks like this:
PieChart chart=new PieChart(ChartType.PIE,conf,series);

Any help is appreciated. Thanks!

Peter