User.Identity.IsAuthenticated always false when calling from restSharp - asp.net-mvc

Question

I have a web application in which I was authenticating user like below
$.ajax({
method: 'POST',
data: JSON.stringify(SaveDetails),
url: Utils.getWebApiUrl() + "/api/account/isLoggedIn",
contentType: "application/json; charset=utf-8",
beforeSend: function (xhr) {
xhr.setRequestHeader('Authorization', 'bearer ' + access_token);
}
})
code in the controller below
[HttpPost]
[Route("api/account/isLoggedIn")]
public IHttpActionResult IsLoggedIn(Dictionary<string, string> Parameters)
//(string UserLoginLogId)
{
if (User?.Identity?.IsAuthenticated == true)
{
if (Parameters.Count() > 0)
{
string userLoginLogId = Convert.ToString(Parameters["UserLoginLogId"]);
string userRefreshToken = Convert.ToString(Parameters["userRefreshToken"]);
if (!string.IsNullOrWhiteSpace(userLoginLogId))
{
DocPro.DMS.BusinessLayer.IAccess.IUser a = (DocPro.DMS.BusinessLayer.IAccess.IUser)DALFinder.GetInstance(typeof(DocPro.DMS.BusinessLayer.IAccess.IUser));
//int LoginTimeOut = Convert.ToInt32(System.Configuration.ConfigurationManager.AppSettings["Login-TimeOut"]);
if (a.IsLoggedInAsPerRefreshToken(Convert.ToInt64(userLoginLogId), userRefreshToken))
return Ok();
else
return NotFound();
}
else
return NotFound();
}
else
return Ok();
}
else
return NotFound();
}
and it was working fine, now I changed the code to the following
Dictionary<string, string> p = new Dictionary<string, string>();
p.Add("UserLoginLogId", Convert.ToString(userId));
p.Add("userRefreshToken", Convert.ToString(RefreshToken));
RestClient client = new RestClient(Convert.ToString(URL));
client.Timeout = -1;
RestRequest request = new RestRequest(Method.POST);
request.RequestFormat = DataFormat.Json;
request.AddJsonBody(p);
request.AddHeader("Content-Type", "application/json");
request.AddHeader("Authorization", "Bearer " + accessToken);
IRestResponse<SPResponse> response = client.Execute<SPResponse>(request);
var result = JsonConvert.DeserializeObject<SPResponse>(response.Content);
but the following key "User?.Identity?.IsAuthenticated" is always showing false and I don't understand the reason.
while I do google I found a solution like below
var isAusorized = (Request.Properties["MS_HttpContext"] as HttpContextWrapper).User.Identity.IsAuthenticated;
but I don't understand how it worked and should I use this or not.