code: private String getRedirectUrl(HttpServletRequest request, String newScheme) {
      String serverName = request.getServerName();
      String uri = request.getRequestURI();
  
      StringBuilder redirect = new StringBuilder(100);
      redirect.append(newScheme);
      redirect.append("://");
      redirect.append(serverName);
      redirect.append(uri);
  
      String query = request.getQueryString();
      if (query != null) {
        redirect.append('?');
        redirect.append(query);
      }
  
      return redirect.toString();
    }
docs: Return the full URL that should be redirected to including query parameters.