code: @Override
      public void writeGraphFiles(BenchmarkReport benchmarkReport) {
          XYPlot plot = createPlot(benchmarkReport);
          int seriesIndex = 0;
          for (SingleBenchmarkResult singleBenchmarkResult : problemBenchmarkResult.getSingleBenchmarkResultList()) {
              XYIntervalSeries series = new XYIntervalSeries(singleBenchmarkResult.getSolverBenchmarkResult().getNameWithFavoriteSuffix());
              XYItemRenderer renderer = new YIntervalRenderer();
              if (singleBenchmarkResult.hasAllSuccess()) {
                  BestSolutionMutationSubSingleStatistic subSingleStatistic = (BestSolutionMutationSubSingleStatistic)
                          singleBenchmarkResult.getSubSingleStatistic(problemStatisticType);
                  List<BestSolutionMutationStatisticPoint> points = subSingleStatistic.getPointList();
                  for (BestSolutionMutationStatisticPoint point : points) {
                      long timeMillisSpent = point.getTimeMillisSpent();
                      long mutationCount = point.getMutationCount();
                      double yValue = mutationCount;
                      // In an XYInterval the yLow must be lower than yHigh
                      series.add(timeMillisSpent, timeMillisSpent, timeMillisSpent,
                              yValue, (yValue > 0.0) ? 0.0 : yValue, (yValue > 0.0) ? yValue : 0.0);
                  }
              }
              XYIntervalSeriesCollection dataset = new XYIntervalSeriesCollection();
              dataset.addSeries(series);
              plot.setDataset(seriesIndex, dataset);
  
              if (singleBenchmarkResult.getSolverBenchmarkResult().isFavorite()) {
                  // Make the favorite more obvious
                  renderer.setSeriesStroke(0, new BasicStroke(2.0f));
              }
              plot.setRenderer(seriesIndex, renderer);
              seriesIndex++;
          }
          JFreeChart chart = new JFreeChart(problemBenchmarkResult.getName() + " best solution mutation statistic",
                  JFreeChart.DEFAULT_TITLE_FONT, plot, true);
          graphFile = writeChartToImageFile(chart, problemBenchmarkResult.getName() + "BestSolutionMutationStatistic");
      }
docs: ************************************************************************