*
   * @param future The future attach the callback to.
   * @param callback The callback to invoke when {@code future} is completed.
   * @param executor The executor to run {@code callback} when the future completes.
   * @since 10.0
   */
  public static <V extends @Nullable Object> void addCallback(
      final ListenableFuture<V> future,
      final FutureCallback<? super V> callback,
      Executor executor) {

    assertThat(units).isEmpty();
  }

  public void testToImmutableEnumSetReused() {
    // The method call lets us capture the accumulator as an A and invoke the callbacks manually
    genericTestToImmutableEnumSetReused(Sets.<SomeEnum>toImmutableEnumSet());
  }

  private static <A extends @Nullable Object> void genericTestToImmutableEnumSetReused(

        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            ElevateWordCA ca = new ElevateWordCA();
            aggsLambda.callback(ca);

        KeyMatchCQ cq = new KeyMatchCQ();
        queryLambda.callback(cq);
        final Collection<FilterFunctionBuilder> list = new ArrayList<>();
        if (functionsLambda != null) {
            functionsLambda.callback((cqLambda, scoreFunctionBuilder) -> {
                KeyMatchCQ cf = new KeyMatchCQ();
                cqLambda.callback(cf);

        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            ClickLogCA ca = new ClickLogCA();
            aggsLambda.callback(ca);
            ca.getAggregationBuilderList().forEach(builder::subAggregation);

        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            RelatedQueryCA ca = new RelatedQueryCA();
            aggsLambda.callback(ca);

        JobLogCQ cq = new JobLogCQ();
        queryLambda.callback(cq);
        final Collection<FilterFunctionBuilder> list = new ArrayList<>();
        if (functionsLambda != null) {
            functionsLambda.callback((cqLambda, scoreFunctionBuilder) -> {
                JobLogCQ cf = new JobLogCQ();
                cqLambda.callback(cf);
                list.add(new FilterFunctionBuilder(cf.getQuery(), scoreFunctionBuilder));

        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            FavoriteLogCA ca = new FavoriteLogCA();
            aggsLambda.callback(ca);

        DuplicateHostCQ cq = new DuplicateHostCQ();
        queryLambda.callback(cq);
        final Collection<FilterFunctionBuilder> list = new ArrayList<>();
        if (functionsLambda != null) {
            functionsLambda.callback((cqLambda, scoreFunctionBuilder) -> {
                DuplicateHostCQ cf = new DuplicateHostCQ();
                cqLambda.callback(cf);

        CrawlingInfoCQ cq = new CrawlingInfoCQ();
        queryLambda.callback(cq);
        final Collection<FilterFunctionBuilder> list = new ArrayList<>();
        if (functionsLambda != null) {
            functionsLambda.callback((cqLambda, scoreFunctionBuilder) -> {
                CrawlingInfoCQ cf = new CrawlingInfoCQ();
                cqLambda.callback(cf);