public static String create() {
    return UuidFactoryImpl.INSTANCE.create();
  }
@Test
  public void create_unique() {
    Set<String> all = new HashSet<>();
    for (int i = 0; i < 50; i++) {
      String uuid = Uuids.create();
      assertThat(uuid).isNotEmpty();
      all.add(uuid);
    }
    assertThat(all).hasSize(50);
  }