public static <T> Iterables<T> iterables() {
    return new Iterables<>();
  }
@Test
  @Category(ValidatesRunner.class)
  public void testFlattenIterablesLists() {
    PCollection<List<String>> input =
        p.apply(Create.<List<String>>of(LINES).withCoder(ListCoder.of(StringUtf8Coder.of())));

    PCollection<String> output = input.apply(Flatten.iterables());

    PAssert.that(output).containsInAnyOrder(LINES_ARRAY);

    p.run();
  }