规范：

public Predicate toPredicate(Root<Hotel> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
    Predicate predicate = root.get("starRating").in(s);
            if (unrated) {
                predicate = cb.or(predicate, cb.isNull(root.get("starRating")));
            }
     return predicate;
}

哪里 s 是一个 Set .
sql日志： Hibernate: select hotel0_.hotel_id as hotel_id1_16_, hotel0_.star_rating as star_ra13_16_ where hotel0_.active=? and (hotel0_.star_rating in () or hotel0_.star_rating is null) order by lower(hotel0_.hotel_name) asc 错误： ERROR 6828 --- [nio-8080-exec-1] o.h.engine.jdbc.spi.SqlExceptionHelper : ERROR: syntax error at or near ")" 例外情况： org.springframework.dao.InvalidDataAccessResourceUsageException: could not extract ResultSet; SQL [n/a]; nested exception is org.hibernate.exception.SQLGrammarException: could not extract ResultSet 我错过了什么？