title: Google Push notifications response
body: <p>all!
  I'm using Google Push Notifications for Gmail API.
  In documents, Google says that server should send a response with status 200, 201, 204 or 102. (<a href="https://cloud.google.com/pubsub/docs/push" rel="nofollow noreferrer">https://cloud.google.com/pubsub/docs/push</a>)
  But when I send this response Google continues to spam me with queries with the same history_id.</p>
  
  <pre><code>def get_new_messages
      # do something with params
      head :ok
  end
  </code></pre>
  
  <p>What should I have besides the status in answer to stop spamming me?
  Thanks!</p>