title: Real-time Developer Notifications Not Sending IAP Subscription Event Messages
body: <p>After setting up Android real-time developer notifications (RTDN) as a way to receive IAP subscription state changes to my web server, I only actually receive a certain push from Google's RTDN webhook that never includes the subscription details.  Below is the payload structure that gets delivered to my server every time a purchase subscription event happens from my app:</p>
  
  <pre><code>"message": {
      "data": "longstringofcharacters",
      "messageId": "604411111111111",
      "message_Id": "60442222222222",
      "publishTime": "2019-07-03T11:03:34.076Z",
      "publish_time": "2019-07-03T11:03:34.076Z",
  },
  "subscription": "projects/api-keyname/subscriptions/my-project-name"
  </code></pre>
  
  <p>According to Google's RTDN setup guide (<a href="https://developer.android.com/google/play/billing/realtime_developer_notifications.html" rel="nofollow noreferrer">https://developer.android.com/google/play/billing/realtime_developer_notifications.html</a>), the below format is what I should expect to receive anytime a new subscription is purchased, cancelled, restored, or undergoes any other related state change from a user in my app:</p>
  
  <pre><code>{
    "version": string,
    "packageName": string
    "eventTimeMillis": long
    "subscriptionNotification": SubscriptionNotification
    "testNotification": TestNotification
  }
  </code></pre>
  
  <p>I have gone through Google's RTDN setup guide a number of times, and made sure my topic has granted publisher permissions for "Pub/Sub Publisher" using "google-play-developer-notifications@system.gserviceaccount.com" which Google says is a necessary step; doing this I believe is the reason why I'm able to receive webhook transmissions, but for some reason I don't understand why subscriptions events aren't getting transmitted.</p>
  
  <p>Ultimately, my goal is to receive the correct payload which contains IAP state change details so that automatically syncs with my user database on my server.  </p>
  
  <p>Has anyone experienced this with RTDN when attempting to receive IAP push notifications?  </p>