if (this.itemLabelGenerator != null) {
            if (this.itemLabelGenerator instanceof PublicCloneable) {
                PublicCloneable pc = (PublicCloneable) this.itemLabelGenerator;
                clone.itemLabelGenerator
                        = (CategoryItemLabelGenerator) pc.clone();
            }
            else {
                throw new CloneNotSupportedException(
                        "ItemLabelGenerator not cloneable.");