Chromecast receiver with custom header

Hello I have created the chromecast receiver correctly and I can cast dash , mp4 and hls videos correctly. I also implemented drm license request using licenserequesthandler.

I want to know how can I add custom headers to manifestrequest and segment request? I want to check specific headers for media to be streamed like custom User-Agent, adding extra header.

so far I have done:

```
playbackConfig.manifestRequestHandler = requestInfo => {
--
 // requestInfo.withCredentials = true;
  requestInfo.headers['User-Agent'] = 'Mozilla 6.0 firefox';
 
 
  };
```

but still the useragent is same when the chromecast calls the url.