protected void addItemEntity(EntityCollection entities,
CategoryDataset dataset, int row, int column,
Shape hotspot) {
String tip = null;
CategoryToolTipGenerator tipster = getToolTipGenerator(row, column);
if (tipster != null) {
tip = tipster.generateToolTip(dataset, row, column);
}
String url = null;
CategoryURLGenerator urlster = getItemURLGenerator(row, column);
if (urlster != null) {
url = urlster.generateURL(dataset, row, column);