@Entity
public class Parent implements Serializable {
   @Id
   public long id;
   @OneToMany(mappedBy = "parent", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
   Set<Child> children;
}

@Entity
public class Child implements Serializable {
   @Id
   long id;
   @ManyToOne
   Parent parent;
}

Parent parent = em.getReference(Parent.class, 1L);
em.remove(parent);
em.flush();

Hibernate: select parent0_.id as id35_0_ from Parent parent0_ where parent0_.id=?
Hibernate: select children0_.parent_id as parent2_1_, children0_.id as id1_, children0_.id as id20_0_, children0_.parent_id as parent2_20_0_ from Child children0_ where children0_.parent_id=?
Hibernate: delete from Child where id=?
Hibernate: delete from Child where id=?
Hibernate: delete from Child where id=?
Hibernate: delete from Child where id=?
Hibernate: delete from Parent where id=?

delete from Child where id=?

delete from Child where parent_id=?