public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof YIntervalSeriesCollection)) {
            return false;
        }
        YIntervalSeriesCollection that = (YIntervalSeriesCollection) obj;
        return ObjectUtilities.equal(this.data, that.data);
    }

    /**
     * Returns a clone of this instance.
     *
     * @return A clone.
     *
     * @throws CloneNotSupportedException if there is a problem.
     */
    public Object clone() throws CloneNotSupportedException {
        YIntervalSeriesCollection clone
                = (YIntervalSeriesCollection) super.clone();
        clone.data = (List) ObjectUtilities.deepClone(this.data);
        return clone;