public async Task OnShutDown(ChatShutdownContext ctx)
        {
            _subscription?.Dispose();
            _subscription = null;

            await Task.CompletedTask;
        }
 private async Task OnChatShuttingdown(ShutdownArgs args)
 {
     ChatShutdownContext chatShutdown = new ChatShutdownContext(MessagesObservable);
     await _chatEventHandler?.RunEventHandler(eh =>
     {
         return(eh.OnShutDown(chatShutdown));
     }, ex =>
     {
         _log.Log(LogLevel.Error, _logCategory, "An error occured when the chat service try to dispose observable.", ex);
         throw new ClientException($"An error occured when the chat service try to dispose observable.");
     });
 }