using System;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var Grid = new {Columns= new[]{new {Visible=true,Header="header1",ActualVisibleIndex=3},

                         new {Visible=true,Header="header2",ActualVisibleIndex=2},

                         new {Visible=false,Header="header3",ActualVisibleIndex=5},

                         new {Visible=true,Header="header4",ActualVisibleIndex=1}}

                       };

        var headers = String.Join(",",Grid.Columns.Where(x=>x.Visible && !string.IsNullOrEmpty(x.Header)).OrderBy(x=>x.ActualVisibleIndex)

            .Select(x=>"{"+x.Header+"}"));

        headers.Dump();

    }

}