老师，下午好，请教一个问题，

public class LoginAdminGatewayFilter implements GatewayFilter, Ordered {
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        ....
        if (token == null || token.isEmpty()) {
            LOG.info("token为空，请求被拦截");
            exchange.getResponse().setStatusCode(HttpStatus.UNAUTHORIZED);
            return exchange.getResponse().setComplete();
        }
        ...
    }
}

请问一下老师，这里 exchange.getResponse() 的返回值 是interface ServerHttpResponse类型，为什么可以 .setStatusCode(HttpStatus.UNAUTHORIZED); 呢？

谢谢老师解答 ！