Private Messages NOT are reaching the subscribers - spring-mvc

Question

I'm Extending this git'let project to send/receive private messages - targeted only to specific subscribed users. I'm able to send it, but subscribers are not receiving them. I've added the forked full code here, below is a snippet of just the important parts of the code.
Config:
#Configuration
#EnableScheduling
#EnableWebSocketMessageBroker
public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {
#Autowired
private SessionBasedHandshakeHandler handshakeHandler;
#Override
public void configureMessageBroker(MessageBrokerRegistry config) {
config.enableSimpleBroker("/topic", "/queue");
config.setApplicationDestinationPrefixes("/app");
}
#Override
public void registerStompEndpoints(StompEndpointRegistry registry) {
registry.addEndpoint("/gs-guide-websocket").setHandshakeHandler(handshakeHandler).withSockJS();
}
}
Controller:
#Controller
public class GreetingController {
#Autowired
public SimpMessageSendingOperations messagingTemplate;
private Set<String> users = new HashSet<>();
#GetMapping("/subscribe4PrivateMsgs")
public #ResponseBody String enablePrivateMessages(HttpSession session) {
String sessionId = session.getId();
users.add(sessionId);
return sessionId;
}
#MessageMapping("/hello")
#SendTo("/topic/greetings")
public Greeting greeting(HelloMessage message) throws Exception {
Thread.sleep(1000); // simulated delay
return new Greeting("Hello, " + message.getName() + "!");
}
#Scheduled(fixedDelay = 5000)
private void sendPrivateMessageToScubscribers() {
users.forEach((sessionId) -> {
SimpMessageHeaderAccessor headerAccessor = SimpMessageHeaderAccessor.create(SimpMessageType.MESSAGE);
headerAccessor.setSessionId(sessionId);
headerAccessor.setLeaveMutable(true);
String msg = sessionId + ":" + GregorianCalendar.getInstance().getTimeInMillis();
Greeting response = new Greeting(msg);
//Tried the following to Send Private Message, but it doens't works
messagingTemplate.convertAndSendToUser(sessionId, "/queue/private", response,
headerAccessor.getMessageHeaders());
//The following reached UI successfully - but to all users
/*response.setContent("Public Msg:: " + msg);
messagingTemplate.convertAndSend("/topic/greetings", response);*/
});
}
}
UI:
function connect() {
$.get("/subscribe4PrivateMsgs", function(userId) {
var socket = new SockJS('/gs-guide-websocket');
stompClient = Stomp.over(socket);
stompClient.connect({}, function (frame) {
setConnected(true);
console.log('Connected: ' + frame);
stompClient.subscribe('/topic/greetings', function (greeting) {
showGreeting('Received Public Msg: ' + JSON.parse(greeting.body).content);
});
stompClient.subscribe('/user/queue/private', function (greeting) {
showGreeting('1 Received Private Msg: ' + JSON.parse(greeting.body).content);
});
stompClient.subscribe('/user/'+userId+'/queue/private', function (greeting) {
showGreeting('2 Received Private Msg: ' + JSON.parse(greeting.body).content);
});
});
});
}

Answer 1

Turns out that this line was causing issues.
messagingTemplate.convertAndSendToUser(sessionId, "/queue/private", response, headerAccessor.getMessageHeaders());
Changing it to
messagingTemplate.convertAndSendToUser(sessionId, "/queue/private", response);
resolved the issue. Github updated with a working copy.