@Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final ObjectReference other = (ObjectReference) obj;
        if (this._indirectObjectNumber != other._indirectObjectNumber) {
            return false;
        }
        return true;
    }