title: How to obtain widevine payload (challenge) in google cast?
body: <p>I'm developing my own Custom Receiver Application and the stream I want to play is protected with widevine, I need to obtain my license from my own server and I need to pass content_id and payload. This my code:</p>
  <pre><code>playbackConfig.protectionSystem = cast.framework.ContentProtection.WIDEVINE;
  
  playbackConfig.licenseRequestHandler = requestInfo =&gt; {
  
      requestInfo.headers[&quot;Authorization&quot;] = token;
      requestInfo.headers[&quot;Content-Type&quot;] = &quot;application/json&quot;;
  
      requestInfo.content = JSON.stringify({ 
          type: &quot;widevine&quot;, 
          type_request: &quot;license&quot;,
          content_id: content_id, 
          payload: &lt;&lt;missing_data&gt;&gt;
      });
  
      return requestInfo
  };
  </code></pre>
  <p>I have it implemented on Android implmementing my own MediaDrmCallback and the class KeyRequest contains the needed information but the param content from object requestInfo doesn't provide that information</p>