@Override
  public boolean isEmpty() {
    return sideInputs.isEmpty();
  }
@Test
  public void testIsEmptyFalse() {
    PCollectionView<Iterable<String>> view =
        Pipeline.create().apply(Create.of("1")).apply(View.asIterable());
    SideInputHandler sideInputHandler =
        new SideInputHandler(ImmutableList.of(view), InMemoryStateInternals.<Void>forKey(null));

    assertFalse(sideInputHandler.isEmpty());
  }