public override async Task OnConnectedAsync()
{
var isOnline = await _tracker.UserConnected(Context.User.GetUsername(), Context.ConnectionId);
if (isOnline)
{
await Clients.Others.SendAsync("UserIsOnline", Context.User.GetUsername());
}
var currentUsers = await _tracker.GetOnlineUser();
await Clients.Caller.SendAsync("GetOnlineUsers", currentUsers);
}