正在使用Spring Webclient下载文件，文件为空

import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.web.reactive.function.client.WebClient;

public class FileDownloader {
    public static void main(String[] args) {
        WebClient webClient = WebClient.create();

        webClient.get()
                .uri("http://example.com/file.txt")
                .accept(MediaType.APPLICATION_OCTET_STREAM)
                .exchange()
                .flatMap(response -> {
                    if (response.statusCode().is2xxSuccessful()) {
                        // 获取文件名
                        String fileName = response.headers().asHttpHeaders().getFirst(HttpHeaders.CONTENT_DISPOSITION);
                        // 获取文件内容并保存到本地
                        return response.bodyToMono(byte[].class)
                                .doOnNext(content -> saveFile(content, fileName));
                    } else {
                        return Mono.error(new RuntimeException("File download failed with status: " + response.statusCode()));
                    }
                })
                .block();
    }

    private static void saveFile(byte[] content, String fileName) {
        // 保存文件到本地
        // ...
    }
}