@ValidateTypeFailure
    public Integer offset;

    @ValidateTypeFailure
    public Integer pn;

    @Size(max = 1000)
    public String sdh;

    @Size(max = 100)
    public String track_total_hits;

    // advance

    @Override
    public int getStartPosition() {
        if (start == null) {
            start = ComponentUtil.getFessConfig().getPagingSearchPageStartAsInteger();
        }