how to print complete http request in reactive spring

Question

I have implemented custom web filter and trying to read complete HTTP request but getting an error on subscribing

public class AppWebFilter implements WebFilter {

@Override
    public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
        exchange.getRequest().getBody().map(m->m.read()).doOnNext(k->k.byteValue()).subscribe();
        return chain.filter(exchange);
    }
}