Error running application after upgrade to core 2.0 about aspnetcore.identity.documentdb HOT 5 OPEN

    public class JsonClaimsPrincipalConverter : JsonConverter
    {
        public override bool CanConvert(Type objectType)
        {
            return (objectType == typeof(ClaimsPrincipal));
        }

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            var objectToSerialize = new { }; //create the object you want to serialize here, based on your dynamic conditions
            new JsonSerializer().Serialize(writer, objectToSerialize); //serialize the object to the current writer
        }

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            throw new NotImplementedException();
        }
    }

public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
 {
            IList<Claim> claims = new List<Claim>();
            JToken jt = JObject.ReadFrom(reader);
            for (int i = 0; i < jt.Count(); i++)
            {
                string type = jt.Values<string>("Type").FirstOrDefault();
                string value = jt.Values<string>("Value").FirstOrDefault();
                string valueType = jt.Values<string>("ValueType").FirstOrDefault();
                string issuer = jt.Values<string>("Issuer").FirstOrDefault();
                string originalIssuer = jt.Values<string>("OriginalIssuer").FirstOrDefault();
                claims.Add(new Claim(type, value, valueType, issuer, originalIssuer));

            }
            return claims;
}