fix coedition

src/main/java/fr/jaquin/bdlg/planner/websockets/SubscriptionListener.java

@@ -42,7 +42,7 @@ public class SubscriptionListener extends SubscriptionMap
 
         // Notify new joiner of other editor of this planning
         msg.setType(StompQuery.planningCoeditor);
-        msg.setPayload("[" + String.join(",", map.get(uuid)) + "]");
+        msg.setPayload("[\"" + String.join("\",\"", map.get(uuid)) + "\"]");
         simpMessagingTemplate.convertAndSendToUser(username, "/queue/query", msg);
 
         // Notify other user that username join