public static <InputT> UsingBuilder<InputT> of(PCollection<InputT> input) {
    return named(null).of(input);
  }
@Test
  public void testBuild_ImplicitName() {
    final PCollection<String> dataset = TestUtils.createMockDataset(TypeDescriptors.strings());
    final PCollection<String> mapped =
        FlatMap.of(dataset).using((String s, Collector<String> c) -> c.collect(s)).output();
    final FlatMap map = (FlatMap) TestUtils.getProducer(mapped);
    assertFalse(map.getName().isPresent());
  }