Java SSE Server with com.sun.net.httpserver.HttpServer

Question

How can implement SSE Server with com.sun.net.httpserver.HttpServer
I wrote simple HttpHandler like this for testing connection:

public class SseResource implements HttpHandler {

    @Override
    public void handle(HttpExchange exchange) throws IOException {
        Headers responseHeaders = exchange.getResponseHeaders();
        responseHeaders.add("Content-Type", "text/event-stream");
        responseHeaders.add("Connection", "keep-alive");
        responseHeaders.add("Transfer-Encoding", "chunked");
        responseHeaders.add("X-Powered-By", "Native Application Server");

        exchange.sendResponseHeaders(200, responseHeaders.size());
        OutputStream writer = exchange.getResponseBody();
        for (int i = 0; i < 10; i++) {
            writer.write("event: count\n".getBytes()); // <-- Connection Closed at this line 
            writer.write(("data: " + i + "\n").getBytes());
            writer.write("\n\n".getBytes());
            writer.flush();
            sleep();
        }

        writer.close();
    }


    public static void sleep() {
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}    

Does not work.
I test connection with Linux curl command:

curl -Ni http://localhost:8080/stream

HTTP/1.1 200 OK
Connection: keep-alive
X-powered-by: Native Application Server
Date: Thu, 10 Jun 2021 05:27:56 GMT
Transfer-encoding: chunked
Content-type: text/event-stream
Content-length: 4

curl: (18) transfer closed with outstanding read data remaining

Did I misunderstand about SSE server? or does my code have a problem?

Answer 1

response size should be zero.
I compare my response headers with result of this project: https://github.com/enkot/SSE-Fake-Server

exchange.sendResponseHeaders(200, 0);