final PersistenceManager pm = pmf.createPersistenceManager();
pm.insert(new EntityWithNewSimpleField(id, "existing", "new"));
//Then
final EntityWithNewSimpleField found = pm.find(EntityWithNewSimpleField.class, id);
assertThat(found).isNotNull();
assertThat(found.getUnmappedField()).isEqualTo("UNMAPPED");
assertThat(pm.getProxy(EntityWithNewSimpleField.class, id).getUnmappedField()).isEqualTo("UNMAPPED");