public Object clone() throws CloneNotSupportedException {
        XYIntervalSeriesCollection clone
                = (XYIntervalSeriesCollection) super.clone();
        int seriesCount = getSeriesCount();
        clone.data = new java.util.ArrayList(seriesCount);
        for (int i = 0; i < this.data.size(); i++) {
            clone.data.set(i, getSeries(i).clone());
        }
        return clone;