public IActionResult SyncCookies() {
  foreach(string cookieName in Request.Cookies.Keys) {
    string pattern = @ "^(_vis_opt_|_vwo).*";
    Regex regex = new Regex(pattern, RegexOptions.IgnoreCase);
    Match match = regex.Match(cookieName);
    if (match.Success) {
      string cookieValue = Request.Cookies[cookieName];
      CookieOptions option = new CookieOptions();
      UInt64 expiry = 315360000000 UL;
      // Expire any VWO cookies after 10 years.
      // Set the cookie on root path so that it's accessible on all paths
      // Set the domain to .<eTld+1>
      option.Expires = DateTime.Now.AddMilliseconds(expiry);
      option.Path = "/";
      option.Domain = ".<eTld+1";
      Response.Cookies.Append(cookieName, cookieValue, option);
    }
  }
  Response.Headers.Add("Access-Control-Allow-Origin", "*");
  return Ok();
}