@Test
public void testRetrieveUser() {

    Optional<User> userOptional = engine.retrieveUser(username);
    assertTrue(userOptional.isPresent());
    User user = userOptional.get();
    assertEquals(user.getResource().stringValue(), userId);
    assertTrue(user.getPassword().isPresent());
    assertEquals(user.getPassword().get().stringValue(), password);
}