我有以下实体：

@Getter
@Setter
@NoArgsConstructor
@MappedSuperclass
public class BaseEntity implements Serializable{

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    public BaseEntity(Long id) {
        this.id = id;
    }

    public boolean isNew(){
        return this.id == null;
    }
}

和

@Setter
@Getter
@NoArgsConstructor
@Entity
@DynamicUpdate
@Table(name = "project")
public class Project extends BaseEntity{

    private static final long serialVersionUID = 1L;

    @Column
    @NotBlank(message = "Name property cannot be null or empty")
    private String name;

    @Column
    private String description;

    @Column
    private LocalDateTime created;

    @Column
    private Long parentId;

    @OneToMany(mappedBy = "parentId", cascade = { CascadeType.ALL }, fetch = FetchType.EAGER)
    private Set<Project> subprojects = new HashSet<>();

    @Builder
    public Project(Long id, String name, String description, LocalDateTime created, Long parentId) {
        super(id);
        this.name = name;
        this.description = description;
        this.created = created;
        this.parentId = parentId;
}

和常规存储库：

@Repository
public interface ProjectRepository extends JpaRepository<Project, Long>{
}

下面是集成测试类：

@DataJpaTest
class ProjectRepositoryIT {

    @Autowired
    TestEntityManager testEntityManager;

    @Autowired
    ProjectRepository projectRepository;

    @Test
    @Transactional
    void testSaveSubproject() {
        Project parent = Project.builder().name("parent").build();
        parent = testEntityManager.persistAndFlush(parent);

        Project child = Project.builder().name("child").parentId(parent.getId()).build();
        child = testEntityManager.persistAndFlush(child);

        var optionalParent = projectRepository.findById(parent.getId());

        if(optionalParent.isPresent()) {
            var foundParent = optionalParent.get();

            assertEquals(parent.getId(), foundParent.getId());
            assertEquals(1, foundParent.getSubprojects().size());

            Optional<Project> matchigProject = foundParent.getSubprojects()
                .stream()
                .filter(p -> p.getId().equals(foundParent.getId()))
                .findFirst();

            assertTrue(matchigProject.isPresent());

            assertEquals(child.getId(), matchigProject.get().getId());
        }else {
            fail("cannot find parent project");
        }
    }
}

问题
我试图测试子项目是否可以通过set正确标记 parentId 财产。我想什么时候 parentId 属性，然后使用此 id 应具有中的子项目信息 subprojects 列表。不幸的Assert assertEquals(1, foundParent.getSubprojects().size()); 失败，因为列表大小为0。我想请教一下我做错了什么？我要宣布我在Spring是新来的。