在 Startup 类中添加如下代码，手动指定 callbackUrl。

public void ConfigureServices(IServiceCollection services)
{
    // ...
    services.AddAuthentication(options =>
    {
        options.DefaultScheme = JwtBearerDefaults.AuthenticationScheme;
    })
    .AddJwtBearer(options =>
    {
        options.Authority = Configuration["Authentication:Authority"];
        options.Audience = Configuration["Authentication:Audience"];
        options.RequireHttpsMetadata = false;
        options.SaveToken = true;
        options.Events = new JwtBearerEvents
        {
            OnMessageReceived = context =>
            {
                if (context.Request.Path.StartsWithSegments("/chat"))
                {
                    var accessToken = context.Request.Query["access_token"];
                    var path = context.HttpContext.Request.Path;
                    var query = context.HttpContext.Request.QueryString;
                    context.Token = accessToken;
                    context.Request.Path = "/chat";
                    context.Request.QueryString = new QueryString("?username=" + context.User.Identity.Name);
                }
                return Task.CompletedTask;
            }
        };
    });
    // ...
}