@Override
  public Optional<WindowType> windowType() {
    return inner.windowType();
  }
@Test
  public void shouldReturnInnerWindowType() {
    // Given:
    when(inner.windowType()).thenReturn(Optional.of(WindowType.SESSION));
    givenNoopTransforms();

    // When:
    final Optional<WindowType> windowType = materialization.windowType();

    // Then:
    assertThat(windowType, is(Optional.of(WindowType.SESSION)));
  }