code: func addRequiredHeadersToRedirectedRequests(req *http.Request, via []*http.Request) error {
  	if len(via) != 0 && via[0] != nil {
  		if trustedLocation(req) && trustedLocation(via[0]) {
  			req.Header = via[0].Header
  			return nil
  		}
  		for k, v := range via[0].Header {
  			if k != "Authorization" {
  				for _, vv := range v {
  					req.Header.Add(k, vv)
  				}
  			}
  		}
  	}
  	return nil
  }
docs: // addRequiredHeadersToRedirectedRequests adds the necessary redirection headers
  // for redirected requests