Connect call Post method encountered 415 Unsupported Media Type: [no body]

I have a problem, Connect call Post method encountered 415 Unsupported Media Type: [no body], how to solve?? Is there something wrong with my writing? I need answers fast. thank you.

  @Autowired
    private final AtlassianHostRestClients atlassianHostRestClients;

    public TestController(AtlassianHostRestClients atlassianHostRestClients) {
        this.atlassianHostRestClients = atlassianHostRestClients;
    }

    @GetMapping("/test")
    public String helloWorld() {
        return "test";
    }

    @RequestMapping(value = "/covertPage", method = RequestMethod.POST, consumes = MediaType.APPLICATION_JSON_VALUE)
    @ContextJwt
    @ResponseBody
    public Result<String> covertPage(@AuthenticationPrincipal AtlassianHostUser hostUser) throws JsonProcessingException {
        String html;
        String content = atlassianHostRestClients.authenticatedAs(hostUser).getForObject("/rest/api/content/" + 16973836 + "?expand=body.view", String.class);
        JSONObject jsonObject = JSONObject.parseObject(content);
        if (Objects.nonNull(jsonObject)) {
            if (Objects.nonNull(jsonObject.getJSONObject("body"))) {
                html = jsonObject.getJSONObject("body").getJSONObject("view").get("value").toString();
                JsonNodeFactory jnf = JsonNodeFactory.instance;
                ObjectNode payload = jnf.objectNode();
                payload.put("value", html);
                payload.put("representation", "view");

                ObjectMapper mapper = new ObjectMapper();
                String a = mapper.writeValueAsString(payload);

                ResponseEntity responseEntity = atlassianHostRestClients.authenticatedAs(hostUser).postForObject("/rest/api/contentbody/convert/export_view", payload.toString(), ResponseEntity.class);

                if(Objects.nonNull(responseEntity)){
                    return Result.success(responseEntity.getStatusCode().toString());
                }
            }
        }

        return Result.success("success");
    }

The screenshot of the problem is as follows: