title: TOC content over write issue
body: <p>Am trying to create TOC from merged file and need TOC as my first page.Now am facing an issue when the toc have more data, its over written to same file.my expectation is to create a new page in the existing toc.pdf file  and write remaining TOC content.</p>
  
  <pre><code>PdfReader tocReader = new PdfReader("toc.pdf");
  page = copy.getImportedPage(tocReader, 1);
  stamp = copy.createPageStamp(page);
  int tocPageCount = 1;
  Paragraph paragraph;
  PdfAction action;
  PdfAnnotation link;
  float y = 770;
  PdfImportedPage newPage = null;
  Rectangle pagesize = tocReader.getPageSize(1);
  ColumnText colTxt = new ColumnText(stamp.getOverContent());
  colTxt.setSimpleColumn(36, 36, 559, y);
  for (TocModel tocModel : toc) {
      paragraph = new Paragraph(tocModel.getTitle());
      paragraph.add(new Chunk(new DottedLineSeparator()));
      paragraph.add(String.valueOf(tocModel.getPageNo()));
      colTxt.addElement(paragraph);
      colTxt.go();
      // seting toc action
      action = PdfAction.gotoLocalPage("p" + tocModel.getPageNo(), false);
      link = new PdfAnnotation(copy, 36, colTxt.getYLine(), 559, y,action);
      stamp.addAnnotation(link);
      y = colTxt.getYLine();
  }
  
  int status = colTxt.go();
  status = colTxt.go();
  if (ColumnText.hasMoreText(status)) {
      PdfContentByte canvas = stamp.getOverContent();
      canvas.addTemplate(page, 0, 0);
      colTxt.setCanvas(canvas);
      colTxt.setSimpleColumn(new Rectangle(36, 36, 559, 806));
      colTxt.go();
  }
  
  stamp.alterContents();
  copy.addPage(page);
  document.close();
  logger.info("Finished TOC !!!");
  
  tocReader = new PdfReader(bos.toByteArray());
  noOfPages =tocReader.getNumberOfPages();
  tocReader.selectPages(String.format("%d, 1-%d", noOfPages, noOfPages - 1));
  PdfStamper stamper = new PdfStamper(tocReader, new FileOutputStream(outPutDirectory + "merge.pdf"));
  
  stamper.close();
  logger.info("merging completed!!!");
  </code></pre>
  
  <p>i refer the following code
  <a href="https://stackoverflow.com/questions/28590487/adding-table-to-existing-pdf-on-the-same-page-itext">Adding table to existing PDF on the same page - ITEXT</a></p>
  
  <p>current output file:</p>
  
  <p><a href="https://i.stack.imgur.com/XafyX.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/XafyX.jpg" alt="current output file"></a></p>