this.task = task;
    }

    @Override
    public void run() {}

    private void setOwner(Thread thread) {
      super.setExclusiveOwnerThread(thread);
    }

    @VisibleForTesting
    @CheckForNull
    Thread getOwner() {
      return super.getExclusiveOwnerThread();
    }

    @Override
    public String toString() {
      return task.toString();
    }
  }

    return new FluentIterable<T>() {
      @Override
      public UnmodifiableIterator<T> iterator() {
        return preOrderIterator(root);
      }

      @Override
      public void forEach(Consumer<? super T> action) {
        checkNotNull(action);
        new Consumer<T>() {
          @Override
          public void accept(T t) {
            action.accept(t);
            children(t).forEach(this);
          }

    @Override
    protected String asEsIndex() {
        if (indexName == null) {
            final String name = ComponentUtil.getFessConfig().getIndexConfigIndex();
            indexName = super.asEsIndex().replaceFirst(Pattern.quote("fess_config"), name);
        }
        return indexName;
    }

    @Override
    protected String asEsIndex() {
        if (indexName == null) {
            final String name = ComponentUtil.getFessConfig().getIndexConfigIndex();
            indexName = super.asEsIndex().replaceFirst(Pattern.quote("fess_config"), name);
        }
        return indexName;
    }

    @Override
    protected String asEsIndex() {
        if (indexName == null) {
            final String name = ComponentUtil.getFessConfig().getIndexConfigIndex();
            indexName = super.asEsIndex().replaceFirst(Pattern.quote("fess_config"), name);
        }
        return indexName;
    }

    @Override
    protected String asEsIndex() {
        if (indexName == null) {
            final String name = ComponentUtil.getFessConfig().getIndexConfigIndex();
            indexName = super.asEsIndex().replaceFirst(Pattern.quote("fess_config"), name);
        }
        return indexName;
    }

    @Override
    protected String asEsIndex() {
        if (indexName == null) {
            final String name = ComponentUtil.getFessConfig().getIndexConfigIndex();
            indexName = super.asEsIndex().replaceFirst(Pattern.quote("fess_config"), name);
        }
        return indexName;
    }

    @Override
    protected String asEsIndex() {
        if (indexName == null) {
            final String name = ComponentUtil.getFessConfig().getIndexConfigIndex();
            indexName = super.asEsIndex().replaceFirst(Pattern.quote("fess_config"), name);
        }
        return indexName;
    }

    @Override
    protected String asEsIndex() {
        if (indexName == null) {
            final String name = ComponentUtil.getFessConfig().getIndexConfigIndex();
            indexName = super.asEsIndex().replaceFirst(Pattern.quote("fess_config"), name);
        }
        return indexName;
    }

  @Override
  Collection<Integer> createUnfiltered(Iterable<Integer> contents) {
    return Lists.newArrayList(contents);
  }

  @Override
  Collection<Integer> filter(Collection<Integer> elements, Predicate<? super Integer> predicate) {
    return Collections2.filter(elements, predicate);
  }