休眠多对一将外键更新为空

我正在尝试使我的@OneToMany和@ManyToOne关系正确。

第1类：

@Entity
public class IdeaProfile {

@Id
@GeneratedValue
private int ideaProfileId;

private String name;

Date dateConcieved;

@OneToOne
@JoinColumn(name="statusCode")  
private Status status;


@OneToMany(fetch=FetchType.EAGER, targetEntity=Pitch.class, cascade=CascadeType.ALL)
@JoinColumn(name = "ideaProfileId") 
private List<Pitch> pitchs;

    ....getters and setters....

第2类：

@Entity
public class Pitch {

@Id
@GeneratedValue
private int id;

@ManyToOne
@JoinColumn(name = "ideaProfileId")
private IdeaProfile ideaProfile;

private Date date;

private String notes;

 ....getters and setters....

当我加载或保存新记录时，这种关系似乎运行良好：

Hibernate: insert into IdeaProfile (dateConcieved, genreCode, name, statusCode) values (?, ?, ?, ?)
Hibernate: insert into Pitch (date, ideaProfileId, notes) values (?, ?, ?)
Hibernate: update Pitch set ideaProfileId=? where id=?

但是，当我尝试更新该记录时，它尝试将IdeaProfileId设置为null：

Hibernate: update IdeaProfile set dateConcieved=?, genreCode=?, name=?, statusCode=?,  where ideaProfileId=?
Hibernate: update Pitch set date=?, ideaProfileId=?, notes=? where id=?
Hibernate: update Pitch set ideaProfileId=null where ideaProfileId=?

当我调试时，我可以看到IdeaProfileId确实在音高对象上设置了...

仅供参考，我不是直接更新从数据库加载的原始对象。这些域映射到UI更新的Model类。因此，在保存/更新时，我将值映射回新的域对象，包括如下所示的ID：

IdeaProfile domain = new IdeaProfile();
domain.setId(model.getIdeaProfileId());
domain.setName(model.getName());
domain.setStatus(model.getStatus());
domain.setDateConcieved(Date.valueOf(model.getDateConvieved()));
for (PitchModel pitch : model.getPitches()) {
     Pitch pitchDomain = new Pitch();
     pitchDomain.setId(pitch.getId());
     pitchDomain.setDate(Date.valueOf(pitch.getDate()));
     pitchDomain.setNotes(pitch.getNotes());
     pitchDomain.setIdeaProfile(domain);
     if(domain.getPitchs() == null ) {
        domain.setPitchs(new ArrayList<Pitch>());
     }
     domain.getPitchs().add(pitchDomain);
 }

openSession();
session.beginTransaction();
session.saveOrUpdate(domain);
session.getTransaction().commit();
closeSession();

有谁知道我做错了什么，所以Hibernate导致更新尝试将IdeaProfileId设置为null？

非常感激。