title: Can't send push notification to Google Smart Display
body: <p>I need to send push notifications to a Google Nest Hub.
  I followed the docs from Google: <a href="https://developers.google.com/assistant/engagement/notifications" rel="nofollow noreferrer">https://developers.google.com/assistant/engagement/notifications</a></p>
  
  <p>The problem is that I can send notifications to smartphones but not to the smart display.</p>
  
  <pre><code>const request = require('request');
  const {google} = require('googleapis');
  const key = require("./Jessa Assistent-730a994db178.json");
  
  const jwtClient = new google.auth.JWT(
    key.client_email, null, key.private_key,
    ['https://www.googleapis.com/auth/actions.fulfillment.conversation'],
    null
  );
  
  jwtClient.authorize((err, tokens) =&gt; {
    if (!err) {
      request.post('https://actions.googleapis.com/v2/conversations:send', {
        auth: {
          bearer: tokens.access_token,
        },
        json: true,
        body: {
          customPushMessage: {
            userNotification: {
              title: 'Push Notification Title',
            },
            target: {
              userId: '&lt;User_ID&gt; (Took this part out of this example)',
              intent: 'High Priority Vragen',
              locale: 'nl-NL'
            },
          },
          isInSandbox: true,
        },
      }, (err, httpResponse, body) =&gt; {
        console.log(`${httpResponse.statusCode}: ${httpResponse.statusMessage}`);
      });
    }
  });
  </code></pre>