Mapped (Inverse) LAZY @OneToMany vs. Unmapped LAZY @OneToMany

package com.greensoft.objectdb.test.console;

import java.util.ArrayList;
import java.util.List;
import javax.persistence.*;

/**
*
* @author Darren Kelly (Webel IT Australia for Greensoft)
*/
public class TestLazyOneToMany {

    /**
     * If true the view/output of the fields of the entities will be called
     * before the relevant finding EntityManager closes.
     */
    final static boolean DO_VIEW_BEFORE_CLOSE = true;

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        String $connection = "objectdb:db/TestLazyOneToMany.tmp;drop";
        EntityManagerFactory emf =
             Persistence.createEntityManagerFactory($connection);

        EntityManager em = emf.createEntityManager();
        em.getTransaction().begin();
        A a = new A("aOwner");

        a.listA_mapped = new ArrayList<A>();
        A aOwnedElement1 = new A("ownedElement1");
        aOwnedElement1.a = a;
        a.listA_mapped.add(aOwnedElement1);
        A aOwnedElement2 = new A("ownedElement2");
        aOwnedElement2.a = a;
        a.listA_mapped.add(aOwnedElement2);

        a.listB_unmapped = new ArrayList<B>();
        a.listB_unmapped.add(new B("b1"));
        a.listB_unmapped.add(new B("b2"));

        em.persist(a);
        em.getTransaction().commit();
        Long id = a.id;
        em.close();

        em = emf.createEntityManager();
        a = em.find(A.class, id);

        if (!DO_VIEW_BEFORE_CLOSE) {
            em.close();
        }

        //Output entities and fields

        System.out.println("a.listA_mapped:" + a.listA_mapped);
            //gives: '[a.listA_mapped:[{A}[4]"ownedElement1", {A}[5]"ownedElement2"]
        System.out.println("a.listB_unmapped:" + a.listB_unmapped);
            //gives: '[]' or '[{B}[2]"b1", {B}[3]"b2"]'

        if (DO_VIEW_BEFORE_CLOSE) {
            em.close();
        }

        emf.close();
    }

    @Entity
    static public class A {

        @Id
        @GeneratedValue
        Long id;
        String name;

        public A(String name) {
            this.name = name;
        }

        @Override
        public String toString() {
            return "{" + getClass().getSimpleName() + "}" + "[" + id + "]\"" + name + "\"";
        }
        @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
        A a; //maps: listA_mapped
        @OneToMany(fetch = FetchType.LAZY, mappedBy = "a", cascade = CascadeType.ALL)
        List<A> listA_mapped;
        @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
        List<B> listB_unmapped;
    }

    @Entity
    static public class B extends A {

        public B(String name) {
            super(name);
        }
    }
}

java -javaagent:objectdb.jar com.greensoft.objectdb.test.console.TestLazyOneToMany

a.listA_mapped:null
a.listB_unmapped:[]