In the app I explicitly set both upper and lower bounds and also tick unit for the BarChart axis:

        numberAxis.setLowerBound(-100.0F);
        numberAxis.setUpperBound(300.0F);
        numberAxis.setTickUnit(100.0F);

After it is rendered the values change:


getLowerBound = -150.0, getUpperBound = 350.0, getTickUnit = 50.0