Newtonsoft.Json contract resolver to allow non-public property setters.

PrivateSetterContractResolver.cs

using System.Reflection;

using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;

// ReSharper disable once CheckNamespace
namespace kwd.gist
{
    /// <summary>
    /// Support serialize properties with non-public setters
    /// </summary>
    public class PrivateSetterContractResolver : DefaultContractResolver
    {
        /// <summary>
        /// Extend base to allow writes for non-public property setter
        /// </summary>
        protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
        {
            var jProperty = base.CreateProperty(member, memberSerialization);

            if (jProperty.Writable) { return jProperty; }

            if(member is PropertyInfo propertyInfo) { jProperty.Writable = propertyInfo.GetSetMethod(true) != null; }
            
            return jProperty;
        }
    }
}