// Find epoch expires when the request will expire.
	epochExpires := d.Unix() + expires

	// Add expires header if not present.
	expiresStr := req.Header.Get("Expires")
	if expiresStr == "" {
		expiresStr = strconv.FormatInt(epochExpires, 10)
		req.Header.Set("Expires", expiresStr)
	}

	// url.RawPath will be valid if path has any encoded characters, if not it will