public Object clone() throws CloneNotSupportedException {
        AbstractPieItemLabelGenerator clone
                = (AbstractPieItemLabelGenerator) super.clone();
        if (this.numberFormat != null) {
            clone.numberFormat = (NumberFormat) this.numberFormat.clone();
        }
        if (this.percentFormat != null) {
            clone.percentFormat = (NumberFormat) this.percentFormat.clone();
        }
        return clone;