@Test
  public void testExists() {

    List<TestEntity> values =
        Arrays.asList(1, 2)
            .stream()
            .map(
                v -> {
                  TestEntity t = new TestEntity();
                  t.setStringProperty(String.format("Hello %s time(s)", v));
                  return t;
                })
            .collect(Collectors.toList());
    repository.save(values);

    assertTrue(repository.exists(values.get(1).getId()));
    assertFalse(repository.exists("3"));
  }