Click on an item in the chart or just hover and look at the tooltip (the reference is a string in JSON format that should contain enough information to identify the chart element):
Performance: JFreeSVG vs BatikJFreeSVGBatikTime to generate 1000 charts in SVG format (lower bars = better performance)Warm-upTest02,0004,0006,0008,00010,00012,00014,00016,00018,00020,00022,00024,000Milliseconds