[undertow-dev] Changing headers on proxy response

Hi, I am currently using a customer handler wrapping the proxy handler. I want to set some response headers from my handler, but if they exist in the response from the proxy's backend, they are overridden. Example code: Undertow.builder() .addHttpListener(8080, "localhost") .setHandler(new MyHandler(new ProxyHandler(proxy, 30000, ResponseCodeHandler.HANDLE_404))).build(); class MyHandler extends HttpHandler { private static final HttpString ACCESS_CONTROL_EXPOSE_HEADERS = new HttpString("Access-Control-Expose-Headers"); private HTTPHandler next; public MyHandler(HttpHandler next) { this.next = next; } public void handleRequest(HttpServerExchange exchange) throws Exception { exchange.getResponseHeaders().put(ACCESS_CONTROL_EXPOSE_HEADERS, "new ACEH"); } } The problem here is that the backend server responds with an Access-Control-Expose-Headers header and that replaces the one I set in MyHandler. Is there any way I can change headers after proxy has received the response from backend and before it starts sending the response to the client? Regards, Jeff