using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CSharpTest
{
    class Program
    {
        static void Main(string[] args)
        {
            var class1 = new Class1[3];
            class1[0] = new Class1() { MyId = 1, Name = "asdasa" };
            class1[1] = new Class1() { MyId = 2, Name = "hahadsa" };
            class1[2] = new Class1() { MyId = 3, Name = "hcxzc" };

            var class2 = new Class2[6];
            class2[0] = new Class2() { Class1Id = 1, CosInnego = "dasdsad" };
            class2[1] = new Class2() { Class1Id = 1, CosInnego = "23178989143y89fdasjbkxad" };
            class2[2] = new Class2() { Class1Id = 2, CosInnego = "adsadasdxzcasqweweqfweauilwer" };
            class2[3] = new Class2() { Class1Id = 2, CosInnego = "dasjopdsaijsdahosaddsad" };
            class2[4] = new Class2() { Class1Id = 2, CosInnego = "dasdadsjiadsiojdasijosad" };
            class2[5] = new Class2() { Class1Id = 3, CosInnego = "dasdszxczklfawqkdwad" };

            var xyz = class1.GroupJoin(class2,
                clazz1 => clazz1.MyId,
                clazz2 => clazz2.Class1Id,
                (clazz1, clazz2List) => new
                {
                    MyName = clazz1.Name,
                    Clazz2List = clazz2List
                });
        }
    }
}