public override void ExecuteResult(ControllerContext context)
 {
     context.HttpContext.Response.Clear();
     context.HttpContext.Response.AddHeader("content-length", PdfStream.Length.ToString());
     context.HttpContext.Response.ContentType = "application/pdf";
     context.HttpContext.Response.AddHeader("content-disposition", $"attachment; filename={this.FileName}");
     context.HttpContext.Response.BinaryWrite(PdfStream.ToArray());
     PdfStream.Dispose();
     PdfStream = null;
 }