code: public static List<Chart> getDetailCharts(ReportLayout reportLayout) {
  		List<Chart> charts = new ArrayList<Chart>();
  
  		Band band = reportLayout.getDetailBand();
  		for (int i = 0, rows = band.getRowCount(); i < rows; i++) {
  			List<BandElement> list = band.getRow(i);
  			for (int j = 0, size = list.size(); j < size; j++) {
  				BandElement be = list.get(j);
  				if (be instanceof ChartBandElement) {
  					charts.add(((ChartBandElement) be).getChart());
  				}
  			}
  		}
  		return charts;
  	}
docs: Get detail band charts for a report layout
  @param reportLayout current report layout
  @return list of charts from detail band