Vaadin Charts. How to change column label text color?

I haven't tried it with column labels, but this  modifies code that works with plotband labels.

Labels out = new Labels(true);
            if( out.getStyle() == null)
                out.setStyle( new Style());
            out.getStyle().setColor(SolidColor.GRAY);
            out.getStyle().setFontSize("8pt");
            column.setDataLabels( out);

Hope it helps

Iain

Thanx, Iain, I higly appreciate your reply, but that didn't work.
I checked it in the code below grabbed from the official demo http://demo.vaadin.com/charts/#ColumnWithNativeDrilldown:

package skpharmacy.components.analysis;

import com.vaadin.addon.charts.ChartOptions;
import com.vaadin.addon.charts.Chart;
import com.vaadin.addon.charts.model.AxisType;
import com.vaadin.addon.charts.model.ChartType;
import com.vaadin.addon.charts.model.Configuration;
import com.vaadin.addon.charts.model.Cursor;
import com.vaadin.addon.charts.model.DataSeries;
import com.vaadin.addon.charts.model.DataSeriesItem;
import com.vaadin.addon.charts.model.Labels;
import com.vaadin.addon.charts.model.PlotOptionsColumn;
import com.vaadin.addon.charts.model.Tooltip;
import com.vaadin.addon.charts.model.XAxis;
import com.vaadin.addon.charts.model.YAxis;
import com.vaadin.addon.charts.model.style.SolidColor;
import com.vaadin.addon.charts.model.style.Style;
import com.vaadin.ui.Component;

@SuppressWarnings("serial")
public class ColumnWithNativeDrilldown {

    public String getDescription() {
        return "Column chart with eager loading drilldown";
    }

    public Component getChart() {
        ChartOptions.get().setTheme(new GrayTheme());
        final Chart chart = new Chart(ChartType.COLUMN);
        chart.setId("chart");

        final Configuration conf = chart.getConfiguration();

        conf.setTitle("Browser market share, April, 2011");
        conf.setSubTitle("Click the columns to view versions. Click again to view brands.");
        conf.getLegend().setEnabled(false);

        XAxis x = new XAxis();
        x.setType(AxisType.CATEGORY);
        conf.addxAxis(x);

        YAxis y = new YAxis();
        y.setTitle("Total percent market share");
        conf.addyAxis(y);

        PlotOptionsColumn column = new PlotOptionsColumn();
        column.setCursor(Cursor.POINTER);
        
// ===== The piece of code supposed to change font color ====

        Labels out = new Labels(true);
        if (out.getStyle() == null) {
            out.setStyle(new Style());
        }
        out.getStyle().setColor(SolidColor.RED);
        out.getStyle().setFontSize("8pt");
        column.setDataLabels(out);

// ===============================================================

        column.getDataLabels().setFormatter("this.y +'%'");

        conf.setPlotOptions(column);

        Tooltip tooltip = new Tooltip();
        tooltip.setHeaderFormat("{series.name}");
        tooltip.setPointFormat("{point.name}: {point.y:.2f}% of total");
        conf.setTooltip(tooltip);

        DataSeries series = new DataSeries();
        series.setName("Browser brands");
        PlotOptionsColumn plotOptionsColumn = new PlotOptionsColumn();
        plotOptionsColumn.setColorByPoint(true);
        series.setPlotOptions(plotOptionsColumn);

        DataSeriesItem item = new DataSeriesItem("MSIE", 55.11);
        DataSeries drillSeries = new DataSeries("MSIE versions");
        drillSeries.setId("MSIE");
        String[] categories = new String[] { "MSIE 6.0", "MSIE 7.0",
                "MSIE 8.0", "MSIE 9.0" };
        Number[] ys = new Number[] { 10.85, 7.35, 33.06, 2.81 };
        drillSeries.setData(categories, ys);
        series.addItemWithDrilldown(item, drillSeries);

        item = new DataSeriesItem("Firefox", 21.63);
        drillSeries = new DataSeries("Firefox versions");
        drillSeries.setId("Firefox");
        categories = new String[] { "Firefox 2.0", "Firefox 3.0",
                "Firefox 3.5", "Firefox 3.6", "Firefox 4.0" };
        ys = new Number[] { 0.20, 0.83, 1.58, 13.12, 5.43 };
        drillSeries.setData(categories, ys);
        series.addItemWithDrilldown(item, drillSeries);

        item = new DataSeriesItem("Chrome", 11.94);
        drillSeries = new DataSeries("Chrome versions");
        drillSeries.setId("Chrome");
        categories = new String[] { "Chrome 5.0", "Chrome 6.0", "Chrome 7.0",
                "Chrome 8.0", "Chrome 9.0", "Chrome 10.0", "Chrome 11.0",
                "Chrome 12.0" };
        ys = new Number[] { 0.12, 0.19, 0.12, 0.36, 0.32, 9.91, 0.50, 0.22 };
        drillSeries.setData(categories, ys);
        series.addItemWithDrilldown(item, drillSeries);

        item = new DataSeriesItem("Safari", 7.15);
        drillSeries = new DataSeries("Safari versions");
        drillSeries.setId("Safari");
        categories = new String[] { "Safari 5.0", "Safari 4.0",
                "Safari Win 5.0", "Safari 4.1", "Safari/Maxthon", "Safari 3.1",
                "Safari 4.1" };
        ys = new Number[] { 4.55, 1.42, 0.23, 0.21, 0.20, 0.19, 0.14 };
        drillSeries.setData(categories, ys);
        series.addItemWithDrilldown(item, drillSeries);

        item = new DataSeriesItem("Opera", 2.14);
        drillSeries = new DataSeries("Opera versions");
        drillSeries.setId("Opera");
        categories = new String[] { "Opera 9.x", "Opera 10.x", "Opera 11.x" };
        ys = new Number[] { 0.12, 0.37, 1.65 };
        drillSeries.setData(categories, ys);
        series.addItemWithDrilldown(item, drillSeries);
        conf.addSeries(series);

        return chart;
    }
}

Any idea what's gone wrong?
May CSS do the trick?
 

Ok, problem is solved.
That's an actual bug of vaadin charts.
I used a little javascript hack

new SizeReporter(this).addResizeListener(new ComponentResizeListener() {
            @Override
            public void sizeChanged(ComponentResizeEvent event) {
                Page.getCurrent().getJavaScript().execute(
                        "       var _el = document.getElementsByClassName('highcharts-drilldown-data-label');"
                        + "     for(i = 0; i < _el.length; i++){        "
                        + "        _el[i].getElementsByTagName('text')[0].style.fill = 'white';               "
                        + "     }"
                );
            }
        });

Here's the best solution:
Put this in css file

.highcharts-drilldown-data-label text{
      fill: white !important;
  }

Thank you, Guillermo.