如何设置正确的json标头？

fetch('https://api.example.com/data', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'Accept': 'application/json'
  },
  body: JSON.stringify({ key: 'value' })
})

import requests
import json

url = 'https://api.example.com/data'
headers = {
    'Content-Type': 'application/json',
    'Accept': 'application/json'
}
data = {
    'key': 'value'
}

response = requests.post(url, headers=headers, data=json.dumps(data))

import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.web.client.RestTemplate;

public class Main {
    public static void main(String[] args) {
        RestTemplate restTemplate = new RestTemplate();
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_JSON);
        headers.set("Accept", MediaType.APPLICATION_JSON_VALUE);
        HttpEntity<String> entity = new HttpEntity<>("{\"key\":\"value\"}", headers);
        String url = "https://api.example.com/data";
        restTemplate.postForObject(url, entity, String.class);
    }
}