CriteraQuery in toPredicate method is not working

Question

I wanted to fetch only select column from the DB using multiple where clause below is my simple implementation. Am getting the result but am getting data for all the column instead of my requested fileName column alone.

List<ImageSiloVO> queryResult = imageSiloRepo.findAll(new Specification<ImageSiloVO>() {

                @Override
                public Predicate toPredicate(Root<ImageSiloVO> root, CriteriaQuery<?>query, CriteriaBuilder criteriaBuilder) {
                    query.select(root.get("fileName"));
                    List<Predicate> predicates = new ArrayList<>();
                    if(StringUtils.isNoneBlank(imageSiloVO.getEntryNumber())) {
                        predicates.add(criteriaBuilder.and(criteriaBuilder.equal(root.get("entryNumber"), imageSiloVO.getEntryNumber())));  
                    }
                    return criteriaBuilder.and(predicates.toArray(new Predicate[predicates.size()]));
                }
            });