EclipseLink @CascadeOnDelete behavior

Question

I'd like to comment about a situation that happened with me today when I was using EclipseLink-JPA. I'll show what was the context and how I solved my issue, but I confess I do not understood what happened.

Consider the following mapping:

class A {
    ...
    @OneToMany(mappedBy = "a")
    @CascadeOnDelete
    List<B> bs;
}

class B {
    ...
    @ManyToOne(optional = false)
    A a;

    @OneToMany(mappedBy = "b")
    @CascadeOnDelete
    List<C> cs;
}

class C {
    ...
    @ManyToOne(optional = false)
    B b;
}

You can notice that there are "delete cascades" between classes A and B and between classes B and C. When I try to delete an object of the B class, everything is ok. However, when I try to delete an object of the A class, a key constraint violation exception occurs. If I ommit the list of C objects of the class B, all works well.

Is this a expected behavior of JPA?

To solve this issue, I created a SQL statement to delete all registers of table B, as may be noted bellow. However, I do not know if there is a more elegant solution.

delete from B b where b.a.id = :aid