code: public CategorySeries addSeries(String seriesName, double[] xData, double[] yData) {
  
      return addSeries(seriesName, xData, yData, null);
    }
docs: Add a series for a Category type chart using using double arrays
  
  @param seriesName
  @param xData the X-Axis data
  @param xData the Y-Axis data
  @return A Series object that you can set properties on