Zwracanie pliku w springu

public File getJsonFile() {
    // utworzenie pewnego JSON'a

    File jsonFile = new File("file.json");

    try (FileWriter fileWriter = new FileWriter(jsonFile)) {
        fileWriter.write(objectMapper.writeValueAsString(json));   // objectMapper z Jackson
    } catch (IOException e) {
        throw new RuntimeException(e);
    }

    return jsonFile;
}

@GetMapping
ResponseEntity<Resource> getJsonFile() throws FileNotFoundException {
    File file = service.getJsonFile();
    String header = String.format("attachment; filename=%s", file.getName());

    return ResponseEntity.ok()
        .header(HttpHeaders.ACCESS_CONTROL_EXPOSE_HEADERS, HttpHeaders.CONTENT_DISPOSITION)
        .header(HttpHeaders.CONTENT_DISPOSITION, header)
        .contentLength(file.length())
        .contentType(MediaType.APPLICATION_JSON)
        .body(new InputStreamResource(new FileInputStream(file)));
}