我在 Neo4j 數(shù)據(jù)庫(kù)中有以下實(shí)體：public class CompetencyEntity {    @GeneratedValue(strategy = UuidStrategy.class)    @Id    private String id;    @Property    private String name;    @Relationship(type = "PARENT_OF", direction = Relationship.OUTGOING)    private List<CompetencyEntity> children;    @Relationship(type = "PARENT_OF", direction = Relationship.INCOMING)            private List<CompetencyEntity> parents;    public void setParentOf(CompetencyEntity competency) {        children.add(competency);    }    public void setNotParentOf(CompetencyEntity competency) {        children.removeIf(comp -> comp.id.equals(competency.id));    }}我想查詢數(shù)據(jù)庫(kù)，以便它返回所有沒(méi)有定義父項(xiàng)的實(shí)體。我想使用@Repository界面自動(dòng)生成的查詢來(lái)完成它。這樣做可以讓我輕松添加@Depth參數(shù)。我的存儲(chǔ)庫(kù)如下：@Repositorypublic interface CompetencyRepository        extends Neo4jRepository<CompetencyEntity, String>, CrudRepository<CompetencyEntity, String> {    Set<CompetencyEntity> findByNameRegex(String name);    @Query("MATCH (n:CompetencyEntity) WHERE NOT (n)<-[:PARENT_OF]-(:CompetencyEntity) RETURN n")    Set<CompetencyEntity> findRootCompetencies();    @Query("MATCH (n:CompetencyEntity) WHERE NOT (:CompetencyEntity)<-[:PARENT_OF]-(n) RETURN n")    Set<CompetencyEntity> findChildrenCompetencies();    Set<CompetencyEntity> findByChildrenEmpty();    Set<CompetencyEntity> findByParentsEmpty();}查詢findRootCompetencies確實(shí)有效。但是當(dāng)我嘗試findByParentsEmpty()（應(yīng)該意味著“找到被調(diào)用的列表parents為空的實(shí)體）方法時(shí)，它會(huì)拋出以下內(nèi)容Exception