@Override
  public Map<TupleTag<?>, PValue> getAdditionalInputs() {
    return delegate().getAdditionalInputs();
  }
@Test
  public void getAdditionalInputsDelegates() {
    Map<TupleTag<?>, PValue> additionalInputs =
        ImmutableMap.of(new TupleTag<>("test_tag"), Pipeline.create().apply(Create.of("1")));
    when(delegate.getAdditionalInputs()).thenReturn(additionalInputs);
    assertThat(forwarding.getAdditionalInputs(), equalTo(additionalInputs));
  }