public boolean equals(Object obj) {
        /*
         * XXX
         *
         * what about  the interval delegate...?
         * The interval width etc wasn't considered
         * before, hence i did not add it here (AS)
         *
         */

        if (obj == this) {
            return true;
        }
        if (!(obj instanceof XYSeriesCollection)) {
            return false;
        }
        XYSeriesCollection that = (XYSeriesCollection) obj;
        return ObjectUtilities.equal(this.data, that.data);