Spring get open websocket connections - spring-boot

Question

I am using Spring Boot Websocket to enable my Spring Boot 2 microservice to deal with websocket connections.
My config:
#Configuration
#EnableWebSocket
public class WsConfig implements WebSocketConfigurer {
#Autowired
WebSocketHandler webSocketHandler;
#Override
public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
DefaultHandshakeHandler handshakeHandler = new DefaultHandshakeHandler();
handshakeHandler.setSupportedProtocols(HANDSHAKE_PROTOCOL);
registry.addHandler(webSocketHandler, WS_HANDLER_PATH + WILDCARD)
.setAllowedOrigins("*")
.setHandshakeHandler(handshakeHandler);
}
}
My clients are able to connect to my Service via Websocket. I am implementing WebSocketHandler interface to handle messages and log connections.
Now my question: Is there a way to show all current websocket users/sessions?
I was trying to use the SimpUserRegistry:
#Configuration
public class UserConfig {
final private SimpUserRegistry userRegistry = new DefaultSimpUserRegistry();
#Bean
public SimpUserRegistry userRegistry() {
return userRegistry;
}
}
and to show the users via a REST endpoint
#RestController
public class WebSocketManager {
private final SimpUserRegistry userRegistry;
public WebSocketManager(SimpUserRegistry userRegistry) {
this.userRegistry = userRegistry;
}
#GetMapping(path = "/users")
public List<String> getConnectedUsers() {
userRegistry.getUsers().stream()
.map(SimpUser::getName)
.forEach(System.out::println);
System.out.println("Users " + userRegistry.getUsers());
System.out.println("UsersCount " + userRegistry.getUserCount());
return this.userRegistry
.getUsers()
.stream()
.map(SimpUser::getName)
.collect(Collectors.toList());
}
}
But this always gives my an empty list: [] even when obviously WS connections are established.
Is this SimpUserRegistry working with the Websocket system of Spring which is configured with the WebSocketConfigurer and #EnableWebSocket? What am I doing wrong? Any tips or alternatives?
Thank you in advance!