NullReferenceException on copy link annotation to new document about itextsharp.lgplv2.core HOT 5 CLOSED

using (var sourceStream = File.Open("input.pdf", FileMode.Open))
{
	using (var documentStream = File.Create("output.pdf"))
	{
		var document = new Document();
		var writer = PdfWriter.GetInstance(document, documentStream);
		writer.PageEmpty = false;

		var reader = new PdfReader(sourceStream);
		reader.ConsolidateNamedDestinations();
		PdfContentByte contentByte = null;

		writer.Outlines = SimpleBookmark.GetBookmark(reader);

		for (int page = 0; page < reader.NumberOfPages; page++)
		{
			document.SetPageSize(reader.GetPageSizeWithRotation(page + 1));

			if (page > 0)
				document.NewPage();
			else
			{
				document.Open();
				contentByte = writer.DirectContent;
			}
					
			var pageData = writer.GetImportedPage(reader, page + 1);
			contentByte.AddTemplate(pageData, 1, 0, 0, 1, 0, 0);

			var links = reader.GetLinks(page + 1);
			foreach (PdfAnnotation.PdfImportedLink link in links)
			{
				var annotation = link.CreateAnnotation(writer);
				writer.AddAnnotation(annotation);
			}
		}

		document.Close();
		documentStream.Seek(0, SeekOrigin.Begin);
	}
}