@Entity
    @Getter
    @Setter
    public static class A {
        @Id
        @GeneratedValue(strategy = AUTO)
        private long id;

        @OneToOne
        private B b;
    }

    @Entity
    @Getter
    @Setter
    public static class B{
        @Id
        @GeneratedValue(strategy = AUTO)
        private long id;

        @OneToOne(mappedBy = "b")
        private A a;
    }

    /**
     * Fails because OneToOne's default fetch type is eager, so even if it loads with an outer join
     * the B relationship, il implies 2 queries because inverse OneToOne in b is eager as well.
     * Removing the inverse OneToOne leads to only one SQL.
     * @throws Exception
     */
    @Test
    public void should_perform_only_one_select_in_owner() throws Exception {
        em.getTransaction().begin();
        final A a = new A();
        final B b = new B();
        a.setB(b);
        em.persist(b);
        em.persist(a);
        em.getTransaction().commit();
        em.clear();

        final SqlCounter counter = new SqlCounter();
        ds.addListener(counter);
        final A a1 = em.find(A.class, a.getId());

        assertThat(a1.getId()).isEqualTo(a.getId());
        assertThat(counter.getCount()).isEqualTo(1); //in fact there's 2 SQL!
    }

Hibernate: select eagero2ote0_.id as id1_0_1_, eagero2ote0_.b_id as b_id2_0_1_, eagero2ote1_.id as id1_1_0_ from EagerO2OTest$A eagero2ote0_ left outer join EagerO2OTest$B eagero2ote1_ on eagero2ote0_.b_id=eagero2ote1_.id where eagero2ote0_.id=?
Hibernate: select eagero2ote0_.id as id1_0_1_, eagero2ote0_.b_id as b_id2_0_1_, eagero2ote1_.id as id1_1_0_ from EagerO2OTest$A eagero2ote0_ left outer join EagerO2OTest$B eagero2ote1_ on eagero2ote0_.b_id=eagero2ote1_.id where eagero2ote0_.b_id=?