class CorsHandler implements HttpHandler, HandlerWrapper {

  boolean validateOrigin(HttpServerExchange exchange) {
    HeaderMap responseHeaders = exchange.getResponseHeaders();
    responseHeaders.put(VARY, "origin");
    String origin = exchange.getRequestHeaders().getFirst(ORIGIN);
    if (origin == null) return true; // just vary
    return setOrigin(origin, responseHeaders);
  }

    CorsHandler(String allowedOrigins);

}