public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof GrayPaintScale)) {
            return false;
        }
        GrayPaintScale that = (GrayPaintScale) obj;
        if (this.lowerBound != that.lowerBound) {
            return false;
        }
        if (this.upperBound != that.upperBound) {
            return false;
        }
        return true;