using System;

using System.Collections.Generic;

using System.Text.Json;

using System.Text.Json.Serialization;

using System.ComponentModel.DataAnnotations.Schema;

using Newtonsoft.Json;

using SystemJsonIgnore =  System.Text.Json.Serialization.JsonIgnoreAttribute;

using JsonSerializer = System.Text.Json.JsonSerializer;

​

public class Program

{

    public class DataValue {

        public string Key { get; set;}

        [SystemJsonIgnore]

        [NotMapped]

        public object Value {get; set;}

    }

​

    public class DataValue<T>: DataValue {

        public new T Value { get; set; }    

    }

    public class StringDataValue : DataValue<string> {

    }

​

    public class IntDataValue : DataValue<int> {

    }

    public class Node {

        public string Key { get; set; }

    }

    public class ModularNode : Node {

        public IList<DataValue> Values { get; set; }

    }

    public static void Main()

    {

        DataValue dataValue = new StringDataValue {

            Key = "SomeKey",

            Value = "Some Value"

        };

        DataValue dataValue2 = new IntDataValue {

            Key = "SomeKey",

            Value = 5

        };

        Node modularNode = new ModularNode {

            Key = "My key",

            Values = new List<DataValue> {

                dataValue, dataValue2

            }

        };

        var serialized = JsonSerializer.Serialize(modularNode, modularNode.GetType());

        Console.WriteLine(serialized);

        var serialized2 = JsonSerializer.Serialize(dataValue, dataValue.GetType());

        Console.WriteLine(serialized2);

        var serialized3 = JsonConvert.SerializeObject(modularNode);

        Console.WriteLine(serialized3);

    }

}