Example confirm signup - but how to auto signin the confirmed user???

AccountController.cs

[AllowAnonymous]
[HttpGet]
[Route("confirm-signup", Name = "ConfirmSignUpRoute")]
public async Task<IHttpActionResult> ConfirmSignUp(string userId = "", string code = "")
{
    IdentityResult confirmEmailResult = await this.AppUserManager.ConfirmEmailAsync(userId, code);

    if (!confirmEmailResult.Succeeded)
    {
        return GetErrorResult(confirmEmailResult);
    }

    IdentityResult addToRolesResult = await this.AppUserManager.AddToRolesAsync(userId, new string[] { "User" });

    if (!addToRolesResult.Succeeded)
    {
        ModelState.AddModelError("", "Failed to add user roles");
        return BadRequest(ModelState);
    }

    // ########################################
    // auto signin confirmed user
    // ########################################
    this.Authentication.SignOut("JWT");
    ApplicationUser user = await this.AppUserManager.FindByIdAsync(userId);
    ClaimsIdentity oAuthIdentity = await user.GenerateUserIdentityAsync(this.AppUserManager, "JWT");
    this.Authentication.SignIn(new AuthenticationProperties() { IsPersistent = true }, oAuthIdentity);
    // where Authentication is a property in the base-controller 
    // ie Request.GetOwinContext().Authentication
    
    Uri redirectLocation = new Uri("http://localhost:8080/#/signup-confirmed");
    return Redirect(redirectLocation);

    //Uri locationHeader = new Uri(Url.Link("GetUserById", new { id = user.Id }));
    //return Created(locationHeader, TheModelFactory.Create(user));
}