using System;

using System.Collections.Generic;

using System.Text.Json;

​

namespace SO_61281096

{

    class Program {

        static void Main(string[] args)

        {

            var json = @"

{ 

    ""people"": {

      ""ID001"": {

        ""id"": ""ID001"",

        ""surame"": ""Smith"",

        ""given"": ""Joe""

      },

      ""ID002"": {

        ""id"": ""ID002"",

        ""surame"": ""Brown"",

        ""given"": ""George""

      }

    }

}";

​

            var options = new JsonSerializerOptions

            {

                PropertyNameCaseInsensitive = true,

            };

            var deserialized = JsonSerializer.Deserialize<Container>(json, options);

            Console.WriteLine(deserialized.People["ID001"].Given); // Joe

        }

    }

​

    public class Container

    {

        public Dictionary<string, Person> People { get; set; }

    }

​

    public class Person

    {

        public string Id { get; set; }

​

        public string Surame { get; set; }

​

        public string Given { get; set; }

    }

}

​

​

​