I wrote a custom gatewayfilter to get the returned response content in filter after the request is completed to see if the request is successful. But at present, only ServerHttpResponse postResponse = exchange.getResponse (); can be obtained, but the data returned by the request cannot be obtained

code is as follows:
return chain.filter (exchange). Then (Mono.fromRunnable (()-> {

       ServerHttpResponse postResponse = exchange.getResponse();
        //responseHttpServletResponseServerHttpResponse 
    }));