651f2d1d75
When a document is updated, users not connected to the collaboration server can override work made by other people connected to the collaboration server. To avoid this, the priority is given to user connected to the collaboration server. If the websocket property in the request payload is missing or set to False, the backend fetch the collaboration server to now if the user can save or not. If users are already connected, the user can't save. Also, only one user without websocket can save a connect, the first user saving acquire a lock and all other users can't save. To implement this behavior, we need to track all users, connected and not, so a session is created for every user in the ForceSessionMiddleware.