`Google::Cloud::PubSub::ReceivedMessage#subscription` returns both subscription and stream

If you receive a message via streaming pull, `ReceivedMessage#subscription` returns the subscriber stream, meaning that if you want to grab the subscription name from it you have to do something like:
```ruby
received_message.subscription.subscriber.subscription_name
```
But if you use the regular pull operation or the `wait_for_messages` method, `ReceivedMessage#subscription` now returns the actual subscription, meaning that the previous line crashes since subscription does not have a subscriber.

Is it possible that both return a subscription? So the streaming pull instead of returning a stream it returns a subscription as the name suggests.