existing example不适合我的场景，它检查是否存在要排序的参数。在我的情况下，我只想按DESC顺序的列（created_on）排序。
因此，下面是我最后要调用的规范的定义，在链接了“其他的：

public static Specification<Event> orderByCreationDate() {
        return new Specification<Event>() {
            @Override
            public Predicate toPredicate(Root<Event> root, CriteriaQuery<?> query, CriteriaBuilder criteriaBuilder) {
                query.orderBy(criteriaBuilder.desc(root.get("created_on")));
                return null;
            }
        };
    }

使用lambda的简化版本如下所示：

public static Specification<Event> orderByCreationDate() {
        return (root, query, criteriaBuilder) -> {
            query.orderBy(criteriaBuilder.desc(root.get("created_on")));
            return null;
        };
    }

以下是规范的完整链接调用：

Page<Event> eventsPage = historyLogRepository.findAllPaginated(
                                    allEventsWithEventTypesByVaultId(vaultId)
                                    .and(hasNoEventTypeVisibility()).or(hasEventTypeVisibility(visibilities))
                                    .and(hasNoEventTypes()).or(hasEventTypes(types))
                                    .and(creationDateBefore(before))
                                    .and(creationDateAfter(after))
                                    .and(hasNoDocumentId()).or(hasDocumentId(documentId))
                                    .and(orderByCreationDate()),
                                    pageable);

我们的想法是替换以下本机查询：

@Query(value = "SELECT * FROM event e " +
            "INNER JOIN event_type et ON et.id = e.event_type_id " +
            "WHERE e.vault_id = :vaultId AND " +
            "(COALESCE(:visibilities) IS NULL OR et.visibility IN (:visibilities)) AND " +
            "(COALESCE(:types) IS NULL OR et.name in (:types)) AND " +
            "(:before IS NULL OR e.created_on < :before) AND " +
            "(:after IS NULL OR e.created_on > :after) AND " +
            "(:documentId IS NULL OR e.document_id = :documentId) " +
            "ORDER BY e.created_on DESC LIMIT :limit", nativeQuery = true)
    List<Event> findAll(@Param("vaultId") String vaultId,
                        @Param("before") LocalDateTime before,
                        @Param("after") LocalDateTime after,
                        @Param("limit") Integer maxNumberOfResults,
                        @Param("types") List<String> types,
                        @Param("visibilities") List<String> visibilities,
                        @Param("documentId") String documented);

新的使用规格：

Page<Event> findAllPaginated(Specification<Event> specification, Pageable pageable);
...

有什么想法吗？在这种情况下，我应该从toPredicate方法返回什么？