code: func (t *tokenRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
  	// if the authorization header already present, use it.
  	if req.Header.Get("Authorization") != "" {
  		return t.RoundTripper.RoundTrip(req)
  	}
  
  	token, err := t.tokenGetter.Token()
  	if err == nil {
  		req.Header.Set("Authorization", "Bearer "+token)
  	} else {
  		klog.V(4).Infof("failed to get token: %s", err)
  	}
  
  	return t.RoundTripper.RoundTrip(req)
  }
docs: // RoundTrip adds the bearer token into the request.