Is possible use custom authentication? about firebase-authentication-dotnet HOT 5 CLOSED

FIRAuth.auth()?.signInWithCustomToken(userMyServerToken) { (user, error) in

}

private const string GoogleCustomAuthUrl = "https://www.googleapis.com/identitytoolkit/v3/relyingparty/verifyCustomToken?key={0}";
public async Task<FirebaseAuthLink> SignInWithCustomTokenAsync(string customToken)
        {
            string content = string.Format("{{\"token\":\"{0}\",\"returnSecureToken\":true}}", new object[1]
            {
                (object) customToken
            });
            FirebaseAuthLink firebaseAuthLink = await this.ExecuteWithPostContentAsync(GoogleCustomAuthUrl, content).ConfigureAwait(false);
            return firebaseAuthLink;
        }

private User GetUser(string idToken)
        {
            var request = (HttpWebRequest)WebRequest.Create("https://www.googleapis.com/identitytoolkit/v3/relyingparty/getAccountInfo?key=" + this.authConfig.ApiKey);
            request.ContentType = "application/json";
            request.Method = "POST";

            using (var streamWriter = new StreamWriter(request.GetRequestStream()))
            {
                string json = new JavaScriptSerializer().Serialize(new
                {
                    idToken = idToken
                });

                streamWriter.Write(json);
            }

            var response = (HttpWebResponse)request.GetResponse();
            using (var streamReader = new StreamReader(response.GetResponseStream()))
            {
                var result = streamReader.ReadToEnd();
                JObject resultJson = JObject.Parse(result);
                IEnumerable<JToken> usersJson = resultJson["users"];
                var user = JsonConvert.DeserializeObject<User>(usersJson.First().ToString());
                return user;
            }
        }