using Newtonsoft.Json; using Newtonsoft.Json.Serialization; namespace Nop.Plugin.Shipping.UPS.API; public class NullToEmptyStringResolver : DefaultContractResolver { protected override IList CreateProperties(Type type, MemberSerialization memberSerialization) { return type.GetProperties() .Select(p => { var jp = base.CreateProperty(p, memberSerialization); jp.ValueProvider = new NullToEmptyStringValueProvider(p); return jp; }).ToList(); } }