* submitted tasks and to collections of tasks submitted via {@code invokeAll}, {@code invokeAny},
   * {@code schedule}, {@code scheduleAtFixedRate}, and {@code scheduleWithFixedDelay}. In the case
   * of tasks submitted by {@code invokeAll} or {@code invokeAny}, tasks will run serially on the
   * calling thread. Tasks are run to completion before a {@code Future} is returned to the caller

    return delegate().invokeAll(tasks, timeout, unit);
  }

  @Override
  public <T extends @Nullable Object> T invokeAny(Collection<? extends Callable<T>> tasks)
      throws InterruptedException, ExecutionException {
    return delegate().invokeAny(tasks);
  }

  @Override
  public <T extends @Nullable Object> T invokeAny(
      Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)

    return delegate.invokeAll(tasks, timeout, unit);
  }

  @Override
  public <T> T invokeAny(Collection<? extends Callable<T>> tasks)
      throws InterruptedException, ExecutionException {
    Preconditions.checkNotNull(tasks, "tasks must not be null!");
    return delegate.invokeAny(tasks);
  }

  @Override
  public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)

    return delegate.invokeAll(tasks, timeout, unit);
  }

  @Override
  public <T> T invokeAny(Collection<? extends Callable<T>> tasks)
      throws InterruptedException, ExecutionException {
    Preconditions.checkNotNull(tasks, "tasks must not be null!");
    return delegate.invokeAny(tasks);
  }

  @Override
  public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)

      throw new UnsupportedOperationException();
    }

    @Override
    public <T> T invokeAny(Collection<? extends Callable<T>> tasks)
        throws ExecutionException, InterruptedException {
      throw new UnsupportedOperationException();
    }

    @Override
    public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)