query.findQueryFilter to find parameter

In controller class:

protected container preRunValidate()
{
    container ret;
    QueryRun                queryRun;
    int cnt,i;
    Query                   query = this.getFirstQuery();
    QueryBuildRange range;
    QueryBuildDataSource    qbds;
    str filter = "";
   
    ret = super();

    qbds = query.dataSourceTable(tablenum(SFA_MembershipTrans));
    queryRun = new QueryRun(query);
 
    if(query.findQueryFilter(qbds,"PaymMode"))      
    {
        ret = [SrsReportPreRunState::Error, "Payment mode is not able to filter in this report"];
    }
   
    if(query.findQueryFilter(qbds,"AmountCur"))      
    {
        ret = [SrsReportPreRunState::Error, "Amount Currency is not able to filter in this report"];
    }
   
    if(query.findQueryFilter(qbds,"AmountMST"))      
    {
        ret = [SrsReportPreRunState::Error, "Amount is not able to filter in this report"];
    }
   
    return ret;
}