Limitation of JPA 1.0 using @IdClass with *nested* composite primary keys?

Question

Given the following example (departments - projects):

A department has the following properties (composite primary key):

@Entity
@IdClass(DeptId.clas         


        

Answer 1

The problem with the posted code is, that JPA 1.0 really doesn't allow nesting of composite primary key classes. This ProjectId is invalid:

public class ProjectId implements Serializable
{
    private String name;
    private DeptId dept;

    ...
}

DeptId has to be flattened, like:

public class ProjectId implements Serializable
{
    private Integer deptNumber;
    private String deptCountry;
    private String name;

    ...
}

I just got an EclipseLink version to go, but Hibernate has problems with that. I wonder how to tell Hibernate that JPA 1.0 is assumed.