How to read headers data in hub SignalR ASP.NET Core 2.1

I'm trying to pass userId to hub on connection to signalR. This is how client sets up the connection:

         connection = new HubConnectionBuilder()
            .WithUrl("http://localhost:56587/hub", options =>
            {
                options.Headers["UserId"] = loginTextBox.Text;
            })
            .AddMessagePackProtocol()
            .Build();

How can I read this header in OnConnectedAsync() method in my hub?

To get Header Value as string:

public override async Task OnConnectedAsync()
{
    var httpCtx = Context.GetHttpContext();
    var someHeaderValue = httpCtx.Request.Headers["UserId"].ToString();
}

Note - You may want to consider passing information in the query string however as not all transports support headers.