Handling Request-Response Logging and JSON Conversion in Feign Logger

Question

I'm encountering an issue while using a custom Feign logger in my Java project. The logger successfully logs request and response data in a specific format, but I'm having trouble converting this format (request) to JSON and dealing with null responses. Here's a snippet of the log format:

request:

--18c87660f01
Content-Disposition: form-data; name="file"; filename="test.txt"
Content-Type: text/plain
Content-Transfer-Encoding: binary

11
--18c87660f01
Content-Disposition: form-data; name="refId"
Content-Type: text/plain; charset=UTF-8

6951c484-06f1-4011-b9fe-2b320ed980c3
--18c87660f01
Content-Disposition: form-data; name="title"
Content-Type: text/plain; charset=UTF-8

test.txt
--18c87660f01
Content-Disposition: form-data; name="lang"
Content-Type: text/plain; charset=UTF-8

I'm looking for guidance on how to convert this format to JSON, ignoring any File objects. Additionally, when the logAndRebufferResponse method is executed, it returns null:

BookResponse response = service.book(bookReq); // The service does not return a null object

Here's the relevant code from my custom Feign logger:

public class FileFeignLogger extends Logger {

    private static final org.slf4j.Logger LOG = LoggerFactory.getLogger(FileFeignLogger.class);
    @Autowired
    private LogService logService;

    @Value("${book.log.directory}")
    private String uploadDirectory;
    @Value("${endpoint}")
    private String endpoint;

    @Override
    protected void logRequest(String configKey, Level logLevel, Request request) {
        InputStream inputStream = new ByteArrayInputStream(request.body());
        System.out.println(getStr(inputStream));
    }

    @Override
    protected Response logAndRebufferResponse(String configKey, Level logLevel, Response response, long elapsedTime)
            throws IOException {
        System.out.println(getStr(response.body().asInputStream()));
//print:
//{"id":"276","refId":"94a2ff55-c28f-49bf-98eb-f16844224d24","status":101,"lastStatusUpdateOn":"24/12/2023 08:20:01"}

        return response;
    }

    private String getStr(InputStream inputStream) {
        try {
            Path tempFile = Paths.get("D:\\development\\log.txt");
            Files.copy(inputStream, tempFile, StandardCopyOption.REPLACE_EXISTING);
            return new String(Files.readAllBytes(tempFile));
        } catch (IOException e) {
            e.printStackTrace();
            return "EX";
        }
    }

    @Override
    protected void log(String configKey, String format, Object... args) {

    }

Translate the request into JSON format, and when the service.book(bookReq) function is called, it should return a non-null object.