@Override
  public String create() {
    return UuidFactoryImpl.INSTANCE.create();
  }
@Test
  public void test_format_of_uuid() {
    String uuid = underTest.create();

    assertThat(uuid.length()).isGreaterThan(10).isLessThan(40);

    // URL-safe: only letters, digits, dash and underscore.
    assertThat(uuid).matches("^[\\w\\-_]+$");
  }