public static <InputT> KeyByBuilder<InputT> of(PCollection<InputT> input) {
    return new Builder<>(null).of(input);
  }
@Test
  public void testBuild_ImplicitName() {
    final PCollection<String> dataset = TestUtils.createMockDataset(TypeDescriptors.strings());
    final PCollection<KV<String, Long>> counted = CountByKey.of(dataset).keyBy(s -> s).output();
    final CountByKey count = (CountByKey) TestUtils.getProducer(counted);
    assertFalse(count.getName().isPresent());
  }