public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof DateAxis)) {
            return false;
        }
        DateAxis that = (DateAxis) obj;
        if (!ObjectUtilities.equal(this.tickUnit, that.tickUnit)) {
            return false;
        }
        if (!ObjectUtilities.equal(this.dateFormatOverride,
                that.dateFormatOverride)) {
            return false;
        }
        if (!ObjectUtilities.equal(this.tickMarkPosition,
                that.tickMarkPosition)) {
            return false;
        }
        if (!ObjectUtilities.equal(this.timeline, that.timeline)) {
            return false;
        }
        if (!super.equals(obj)) {
            return false;
        }
        return true;