using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading.Tasks;

​

public class Program

{

   public static void Main()

    {

      Task.Run(() => AsyncMain()).GetAwaiter().GetResult();

//      Console.ReadLine();

    }

​

    private static async void AsyncMain()

    {

      var listOfIds = new[] { "1", "2" };

      var targetList = new List<string>();

      listOfIds.ToList().ForEach(async x => targetList.AddRange(await GetIssueForProject(x)));

​

      Console.WriteLine(listOfIds.Length);

​

      foreach (var id in listOfIds)

      {

        var issues = await GetIssueForProject(id);

        targetList.AddRange(issues);

      }

​

      Console.WriteLine(listOfIds.Length);

    }

​

    private static async Task<IEnumerable<string>> GetIssueForProject(string projectId)

    {

      return new List<string>{ "something" };

    }

}