using System;

using System.Text.Json;

using System.Text.Json.Serialization;

public class Program

{

    public static void Main()

    {

        string json = @"{

          ""database"": ""abc"",

          ""configuration"": {

            ""class1"": {

              ""property1"": ""prop1""

            },

            ""class2"": {

              ""property2"": ""prop2""

            },

            ""class3"": {

              ""property3"": ""prop3""

            }

          }

        }";

        var data = JsonSerializer.Deserialize<Root>(json);

        data.Dump();

    }

}

​

    public class Class1    

    {

        [JsonPropertyName("property1")]

        public string Property1 { get; set; } 

    }

​

    public class Class2    

    {

        [JsonPropertyName("property2")]

        public string Property2 { get; set; } 

    }

​

    public class Class3    

    {

        [JsonPropertyName("property3")]

        public string Property3 { get; set; } 

    }

​

    public class Configuration    

    {

        [JsonPropertyName("class1")]

        public Class1 Class1 { get; set; } 

        [JsonPropertyName("class2")]

        public Class2 Class2 { get; set; } 

        [JsonPropertyName("class3")]

        public Class3 Class3 { get; set; } 

    }

​

    public class Root    

    {

        [JsonPropertyName("database")]

        public string Database { get; set; }

        [JsonPropertyName("configuration")]

        public Configuration Configuration { get; set; } 

    }