对于双轴条形图，增加jfreechart中两个间隔之间的间距

Question

目前我正在使用JFreeChart绘制双轴条形图。间隔的条形彼此非常接近。因此，图表中未显示间隔标签。如何增加栏之间的空间？

    CategoryAxis domainAxis = new CategoryAxis("Value");
    domainAxis.setAxisLinePaint(Color.blue);
    domainAxis.setLowerMargin(0.05);
    domainAxis.setUpperMargin(0.05);
    NumberAxis rangeAxis = new NumberAxis("Category 2");
    BarRenderer renderer1 = new BarRenderer();
    renderer1.setMaximumBarWidth(.50);
    renderer1.setSeriesPaint(0, Color.blue);
    renderer1.setShadowVisible(false);
    CategoryPlot plot = new CategoryPlot(dataset1, domainAxis, rangeAxis, renderer1);
    JFreeChart chart = new JFreeChart("", plot);
    chart.setBackgroundPaint(Color.WHITE);
    plot.setBackgroundPaint(Color.WHITE);
    plot.setDomainAxisLocation(AxisLocation.BOTTOM_OR_RIGHT);   
    plot.setDataset(1, dataset2);
    plot.mapDatasetToRangeAxis(1, 1);
    ValueAxis axis2 = new NumberAxis("Category 1");
    plot.setRangeAxis(1, axis2);
    plot.setRangeAxisLocation(1, AxisLocation.BOTTOM_OR_RIGHT);
    BarRenderer renderer2 = new BarRenderer();
    renderer2.setSeriesPaint(0, Color.green);
    renderer2.setMaximumBarWidth(.100);
    renderer2.setShadowVisible(false);  
    plot.setRenderer(1, renderer2);
    return chart;

完整的代码：

import java.awt.Dimension;
import javax.swing.JPanel;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.labels.StandardCategoryItemLabelGenerator;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.renderer.category.BarRenderer;
import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;
import org.jfree.ui.ApplicationFrame;
import org.jfree.ui.RefineryUtilities;

public class BarChartDemo7 extends ApplicationFrame {

static class LabelGenerator extends StandardCategoryItemLabelGenerator {

    public String generateLabel(CategoryDataset dataset, int series,
            int category) {
        return dataset.getRowKey(series).toString();
    }
}

public BarChartDemo7(String title) {
    super(title);
    JPanel chartPanel = createDemoPanel();
    chartPanel.setPreferredSize(new Dimension(500, 270));
    setContentPane(chartPanel);
}

private static CategoryDataset createDataset() {

    String series1 = "First";
    String series2 = "Second";
    String series3 = "Third";

    DefaultCategoryDataset dataset = new DefaultCategoryDataset();

    for(int i=0;i<120;i++){
        dataset.addValue(i, series1, Integer.toString(i));
    }

    for(int i=0;i<120;i++){
        dataset.addValue(i, series2, Integer.toString(i));
    }

    for(int i=0;i<120;i++){
        dataset.addValue(i, series3, Integer.toString(i));
    }


    return dataset;

}

private static JFreeChart createChart(CategoryDataset dataset) {


    JFreeChart chart = ChartFactory.createBarChart(
            "Bar Chart Demo 7",       
            "Category",              
            "Value",                  
            dataset,                  
            PlotOrientation.HORIZONTAL, 
            false,                    
            true,                    
            false                  
            );

    CategoryPlot plot = (CategoryPlot) chart.getPlot();
    plot.setRangePannable(true);

    NumberAxis rangeAxis = (NumberAxis) plot.getRangeAxis();
    rangeAxis.setStandardTickUnits(NumberAxis.createIntegerTickUnits());

    BarRenderer renderer = (BarRenderer) plot.getRenderer();
    renderer.setDrawBarOutline(false);
    renderer.setItemMargin(0.10);

    return chart;

}

public static JPanel createDemoPanel() {
    JFreeChart chart = createChart(createDataset());
    ChartPanel panel = new ChartPanel(chart);
    panel.setMouseWheelEnabled(true);
    return panel;
}

public static void main(String[] args) {
    BarChartDemo7 demo = new BarChartDemo7(
            "");
    demo.pack();
    RefineryUtilities.centerFrameOnScreen(demo);
    demo.setVisible(true);
}

}

我想增加间隔之间的间距，使它们不重叠。