QueryRunner query()为何返回多余空对象？

QueryRunner qr = new QueryRunner(C3P0Util.getDataSource());
        List<UnitCN> list = qr.query("select unit,cap_score from t_risk_unit_cn " +
                "where t_time between to_date('2017-11-8 18:00:00','yyyy-mm-dd hh24:mi:ss') " +
                "and to_date('2017-11-8 19:00:00','yyyy-mm-dd hh24:mi:ss')", new BeanListHandler<UnitCN>(UnitCN.class));

集合list中有空值：
数据库执行该sql语句返回4条结果：
这是怎么回事呢？求大家帮忙解答