问itext7不自动创建新pdf页

EN

public void ReplicateBug(string pdfFile)
{
    iText.Kernel.Pdf.PdfWriter writer = null;
    iText.Kernel.Pdf.PdfDocument pdf = null;
    iText.Layout.Document document = null;

    try
    {
        writer = new iText.Kernel.Pdf.PdfWriter(pdfFile);
        pdf = new iText.Kernel.Pdf.PdfDocument(writer);
        document = new iText.Layout.Document(pdf, iText.Kernel.Geom.PageSize.A4);
        document.Add(new iText.Layout.Element.Paragraph("*** PRODUCTS ***"));
        iText.Kernel.Pdf.Canvas.Draw.DashedLine dashedLine = new iText.Kernel.Pdf.Canvas.Draw.DashedLine();
        document.Add(new iText.Layout.Element.LineSeparator(dashedLine));

        iText.Layout.Element.Table table = null;

        for (int i = 0; i < 10; ++i)
        {
            iText.Layout.Element.Cell cell = null;

            table = new iText.Layout.Element.Table(2);
            table.SetMarginTop(10);

            cell = new iText.Layout.Element.Cell().Add("-- PRODUCT --");
            table.AddCell(cell);
            cell = new iText.Layout.Element.Cell(3, 1).Add("image");
            cell.SetHorizontalAlignment(iText.Layout.Properties.HorizontalAlignment.CENTER);
            cell.SetVerticalAlignment(iText.Layout.Properties.VerticalAlignment.MIDDLE);
            table.AddCell(cell);
            cell = new iText.Layout.Element.Cell().Add("Product text." + Environment.NewLine + "Welcome");
            cell.SetHeight(75);
            table.AddCell(cell);
            cell = new iText.Layout.Element.Cell().Add((i + 1).ToString().PadLeft(10, '0'));
            table.AddCell(cell);

            try
            {
                document.Add(table);
                document.Add(new iText.Layout.Element.LineSeparator(dashedLine));   // Default LineWidth is 1
            }
            catch
            {
                // NOTE: After adding 5 tables to the pdf an exception is thrown of the following kind.

                // Exception: "Object reference not set to an instance of an object."
                // Source: "itext.layout"
                // StackTrace: "at iText.Layout.Renderer.TableRenderer.Layout(LayoutContext layoutContext)
                //              at iText.Layout.Renderer.RootRenderer.AddChild(IRenderer renderer)
                //              at iText.Layout.RootElement`1.Add[T2](BlockElement`1 element)
                //              at iText.Layout.Document.Add[T](BlockElement`1 element)
                //              at iTextSharp7_Test.Controllers.PdfController.ReplicateBug(String pdfFile) in C:\\Users\\me\\Documents\\Visual Studio 2015\\Projects\\App_Test\\iTextSharp7_Test\\Controllers\\PdfController.cs:line 443"
            }
        }

        document.Close();
        pdf.Close();
        writer.Close();
    }
    catch
    {
        if (document != null)
        {
            document.Close();
        }

        if (pdf != null)
        {
            pdf.Close();
        }

        if (writer != null)
        {
            writer.Close();
        }

        throw;
    }
}