code: @Override
    public void close() {
      // TODO (dano): fail outstanding futures
      scheduler.shutdownNow();
      try {
        scheduler.awaitTermination(30, SECONDS);
      } catch (InterruptedException e) {
        Thread.currentThread().interrupt();
      }
      closeFuture.complete(null);
      listener.publisherClosed(Publisher.this);
    }
docs: Close this {@link Publisher}. This will also close the underlying {@link Pubsub} client.