Excessive messages are returned when subscribe to /app endpoint multiple times.

[wjx]

One subscribe to @SubscribeMapping should return one message, but when subscribe multiple times, excessive messages are returned:

Client:

stompClient.subscribe('/app/msg', function(msg) {
            console.log("subscribe1 callback");
        });
        stompClient.subscribe('/app/msg', function(msg) {
            console.log("subscribe2 callback");
        });

Server:

@SubscribeMapping("/msg")
	public Greeting msg() {
		return new Greeting("Hello, World!");
	}

Expected:
Two messages with content Hello, World! returned.

But excessive messages are returned.

Logs:

Web Socket Opened...
18:10:24.104 stomp.min.js:8 >>> CONNECT
accept-version:1.1,1.0
heart-beat:10000,10000


18:10:24.173 stomp.min.js:8 <<< CONNECTED
version:1.1
heart-beat:0,0


18:10:24.174 stomp.min.js:8 connected to server undefined
18:10:24.181 app.js?_=dsd:24 Connected: CONNECTED
heart-beat:0,0
version:1.1


18:10:24.182 stomp.min.js:8 >>> SUBSCRIBE
id:sub-0
destination:/app/msg


18:10:24.182 stomp.min.js:8 >>> SUBSCRIBE
id:sub-1
destination:/app/msg


18:10:25.271 stomp.min.js:8 <<< MESSAGE
destination:/app/msg
message-id:559f29a724bd48b794f270b71a18aa71-1
content-type:application/json;charset=UTF-8
subscription:sub-0
content-length:27

{"content":"Hello, World!"}
18:10:25.272 app.js?_=dsd:34 subscribe1 callback
18:10:25.273 stomp.min.js:8 <<< MESSAGE
destination:/app/msg
message-id:559f29a724bd48b794f270b71a18aa71-1
content-type:application/json;charset=UTF-8
subscription:sub-1
content-length:27

{"content":"Hello, World!"}
18:10:25.273 app.js?_=dsd:37 subscribe2 callback
18:10:25.277 stomp.min.js:8 <<< MESSAGE
destination:/app/msg
message-id:559f29a724bd48b794f270b71a18aa71-0
content-type:application/json;charset=UTF-8
subscription:sub-0
content-length:27

{"content":"Hello, World!"}
18:10:25.277 app.js?_=dsd:34 subscribe1 callback
18:10:25.278 stomp.min.js:8 <<< MESSAGE
destination:/app/msg
message-id:559f29a724bd48b794f270b71a18aa71-0
content-type:application/json;charset=UTF-8
subscription:sub-1
content-length:27

{"content":"Hello, World!"}
18:10:25.279 app.js?_=dsd:37 subscribe2 callback

Thanks!