@Override
  public <T extends State> T state(StateNamespace namespace, StateTag<T> address) {
    return workItemState.get(namespace, address, StateContexts.nullContext());
  }
@Test
  public void testBagIsEmptyAfterClear() throws Exception {
    StateTag<BagState<String>> addr = StateTags.bag("bag", StringUtf8Coder.of());
    BagState<String> bag = underTest.state(NAMESPACE, addr);

    bag.clear();
    ReadableState<Boolean> result = bag.isEmpty();
    Mockito.verify(mockReader, never())
        .bagFuture(key(NAMESPACE, "bag"), STATE_FAMILY, StringUtf8Coder.of());
    assertThat(result.read(), Matchers.is(true));

    bag.add("hello");
    assertThat(result.read(), Matchers.is(false));
  }