Hibernate (Spring JPA): @ManyToOne JoinColumns (which are an EmbeddedId) are null

I didn't see my error and after a research on stackoverflow and Google I think the code should be correct. But Hibernate (spring-boot-starter-data-jpa 2.2.4) still fill the JoinColumns with null.

Here is my OneToMany class:

@Entity
@Table(name = "tablea", schema = "")
public class TableAEntity implements Serializable {

    private static final long serialVersionUID = 7890327260188587351L;

    @EmbeddedId
    private MyId id;
    
    @OneToMany(cascade = ALL, mappedBy = "tableA", orphanRemoval = true, fetch = FetchType.LAZY)
    private List<TableBEntity> tableBentries;
    
    // Getter + Setter
}

My EmbeddedId class:

@Embeddable
public class MyId implements Serializable {

    private static final long serialVersionUID = -8267953052238233498L;

    @Column(name = "id")
    private String id;

    @Column(name = "iddate")
    private Date iddate;

    @Column(name = "idint")
    private BigInteger idint;
    
    // Getter + Setter
}

And finally my ManyToOne class:

@Entity
@Table(name = "tableB", schema = "")
public class TableBEntity implements Serializable {

    private static final long serialVersionUID = -4648090658471459969L;

    @Id
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumns({
        @JoinColumn(name = "id", referencedColumnName = "id"),
        @JoinColumn(name = "iddate", referencedColumnName = "iddate"),
        @JoinColumn(name = "idint", referencedColumnName = "idint")
    })
    private TableAEntity tableA;
    
    // Some other attributes
    
    // Getter + Setter
}

As you may see I want to use the attributes (id, iddate and idint) as a combined primaray key in both tables.

When I create the TableAEntity object I add several TableBEntity objects to the tableBentries attribute. And for every TableBEntity I set the reference to the TableAEntity (attribute tableA). And of course the MyId (attribute id) object is filled.

After saveing the TableAEntity object, Hibernate also stores all TableBEntity but the fields id, iddate and idint (all JoinColumn's) are null.

Any idea?

It seems that @Id in my TableBEntity causes the problems. If I moved it to another attribute, it works.