@Override
protected void addQueryParameters(ERXMutableURL chartUrl, WOResponse response, WOContext context) {
super.addQueryParameters(chartUrl, response, context);
WOComponent component = context.component();
chartUrl.setQueryParameter("cht", "p");
NSArray<String> labels = AjaxUtils.arrayValueForAssociation(component, _labels);
if (labels != null) {
chartUrl.setQueryParameter("chl", labels.componentsJoinedByString("|"));