* @see DATAJPA-491
*/
@Test
public void shouldSortMailWithNestedStringBasedSortCriteriaNullsFirst() {
MailUser fooMailUser = new MailUser("foo");
em.persist(fooMailUser);
MailMessage message1 = new MailMessage();
message1.setContent("abc");
MailSender sender1 = new MailSender("foo");