如何访问kafka rest proxy (GET consumers offsets)

如何访问kafka 接口: GET /consumers/(string:group_name)/instances/(string:instance)/offsets

我的代码入下:

String json = "{"partitions":[{"topic":"rest-proxy-test","partition":0}]}";
String baseUrl = "http://slave2.anywhere.com:8082/";
String url = "consumers/my_json_consumer/instances/office_consumer_instance/offsets";
URLConnection connection = new URL(baseUrl + url).openConnection();
Charset charset = StandardCharsets.UTF_8;
connection.setRequestProperty("Accept-Charset", charset.name());

connection.setDoOutput(true);
try (OutputStream output = connection.getOutputStream()) {
output.write(json.getBytes(charset));
}
InputStream response = connection.getInputStream();
try (Scanner scanner = new Scanner(response)) {
String responseBody = scanner.useDelimiter("\A").next();
System.out.println(responseBody);
}

但是调用不成功,请问哪里出了问题

https://docs.confluent.io/2.0.0/kafka-rest/docs/intro.html