public static <T, PredicateT extends ProcessFunction<T, Boolean>> Filter<T> by(
      PredicateT predicate) {
    return new Filter<>(predicate);
  }
@Test
  @Category(NeedsRunner.class)
  public void testNoFilterByPredicate() {
    PCollection<Integer> output =
        p.apply(Create.of(1, 2, 4, 5)).apply(Filter.by(new TrivialFn(false)));

    PAssert.that(output).empty();
    p.run();
  }