public List findByExample(Problem instance) {
		log.debug("finding Problem instance by example");
		try {
			List results = getSession().createCriteria(
					"com.oj.hibernate.daoNdo.Problem").add(
					Example.create(instance)).list();
			log.debug("find by example successful, result size: "
					+ results.size());
			return results;
		} catch (RuntimeException re) {
			log.error("find by example failed", re);
			throw re;
		}
	}