JPA 2.0 hobernate 4&x2B@一元单向集

我读了很多关于@OneToMany的话题和论坛，但不幸的是，这些都帮不上忙

例如，我们有如下实体：

@Entity
@Table(name = "MANAGER")
public class Manager{

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "MAN_ID")
    private long id;

    @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinColumn(name = "MAN_ID", updatable=true)     
    private Set<Workers> workers;

    @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinColumn(name = "MAN_ID", updatable=true)   
    private Set<Helpers> helpers;

...
}

@Entity
@Table(name = "WORKERS")
public class Workers{

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "ID")
    private long id;

...
}

@Entity
@Table(name = "HELPERS")
public class Helpers{

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "ID")
    private long id;

...
}

作为回报，我看到了hibernate是如何尝试进行插入的，但是没有针对Worker和Helper的更新。 当我从DB取回Manager时，两个列表都为空（null）。

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我在这里遗漏了什么？

看起来我遗漏了nullable

@JoinColumn(name = "MAN_ID", nullable = false)  

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您是否将getter和setter设置为public/protected？

@JoinColumn(name = "MAN_ID", nullable = false)