Converting Tiff to PDF: PDF is corrupted

I followed this example of iText 7 to convert a multi-page Tiff into a multi-page PDF, but when I open the PDF it's corrupted. Adobe Reader displays an error and Chrome shows this:

(Every page looks like that, but they aren't identical).

This is the code I used:

File newPdfFile = new File("<path...>/converted_file.pdf");

URL tiffUrl = UrlUtil.toURL("<path...>/original_file.tif");
IRandomAccessSource ras = new RandomAccessSourceFactory().createSource(tiffUrl);
RandomAccessFileOrArray rafoa = new RandomAccessFileOrArray(ras);

int numberOfPages = TiffImageData.getNumberOfPages(rafoa);

PdfDocument pdf = new PdfDocument(new PdfWriter(new FileOutputStream(newPdfFile)));
Document document = new Document(pdf);

for(int i = 1; i <= numberOfPages; ++i) {
    Image image = new Image(ImageDataFactory.createTiff(tiffUrl, true, i, true));
    document.add(image);
}
document.close();
pdf.close();

And this is the code I used with iText 5.5.11, which works but uses a deprecated constructor of RandomAccessFileOrArray:

File newPdfFile = new File("<path...>/converted_file.pdf");

RandomAccessFileOrArray rafoa = new RandomAccessFileOrArray("<path...>/original_file.tif");

int numberOfPages = TiffImage.getNumberOfPages(rafoa);

Document document = new Document();
PdfWriter.getInstance(document, new FileOutputStream(newPdfFile));
document.open();

for (int i = 1; i <= numberOfPages; ++i) {
  Image image = TiffImage.getTiffImage(rafoa, i);
  Rectangle pageSize = new Rectangle(image.getWidth(), image.getHeight());
  document.setPageSize(pageSize);
  document.newPage();
  document.add(image);
}
document.close();

Unfortunately I can't provide sample files because they are confidential/classified...

What could be the issue?

P.S.: I tried with the same tiff used in the example code I followed and it works. What's wrong with my tiffs? In the file properties, other than the dimensions and resolution there's:

Bit depth: 1
Compression: CCITT T.4
Resolution unit: 2

Solution

Ok, thanks to Michaël Demey's suggestions I managed to get the proper pdf using iText 7.

Here's the maven imports:

<dependency>
    <groupId>com.sun.media</groupId>
    <artifactId>jai_imageio</artifactId>
    <version>1.1</version>
</dependency>

<dependency>
    <groupId>com.itextpdf</groupId>
    <artifactId>layout</artifactId>
    <version>7.0.3</version>
</dependency>

And here's the code:

import com.itextpdf.io.image.ImageDataFactory;
import com.itextpdf.kernel.geom.PageSize;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.layout.Document;
import com.itextpdf.layout.element.Image;
import java.io.File;
import java.io.FileOutputStream;
import javax.imageio.ImageIO;
import javax.imageio.ImageReader;

[...]

File newPdfFile = new File("<path...>/converted_file.pdf");

ImageReader reader = ImageIO.getImageReadersByFormatName("TIFF").next();
reader.setInput(ImageIO.createImageInputStream(new File("<path...>/original_file.tif")));
int numberOfPages = reader.getNumImages(true);

PdfDocument pdf = new PdfDocument(new PdfWriter(new FileOutputStream(newPdfFile)));
Document document = new Document(pdf);

for(int i = 0; i < numberOfPages; ++i) {// in javax.imageio.ImageReader they start from 0!
    java.awt.Image img = reader.read(i);
    Image tempImage = new Image(ImageDataFactory.create(img, null));
    pdf.addNewPage(new PageSize(tempImage.getImageWidth(), tempImage.getImageHeight()));
    tempImage.setFixedPosition(i + 1, 0, 0);
    document.add(tempImage);
}
document.close();
pdf.close();