iText5 to iText7 - importing page and using PageVerticalAnalyzer for proccesing content

Question

I'm switching some parts of my program from itext5 to itext 7. How can I import pages from others pdf's to a single one?

    void merge(PdfDocument reader, PdfDocumentContentParser parser, int page) throws IOException {

        PdfImportedPage importedPage = writer.getImportedPage(reader, page);
        PdfContentByte directContent = writer.getDirectContent();

        PageVerticalAnalyzer finder = parser.processContent(page, new PageVerticalAnalyzer());

        if (finder.verticalFlips.size() < 2) {
            return;
        }
        Rectangle pageSizeToImport = reader.GetPageSize(page);

        int startFlip = finder.verticalFlips.size() - 1;
        boolean first = true;
        while (startFlip > 0) {
            if (!first) {
                newPage();
            }

            float freeSpace = yPosition - pageSize.getBottom();
            int endFlip = startFlip + 1;
            while ((endFlip > 1) && (finder.verticalFlips.get(startFlip) - finder.verticalFlips.get(endFlip - 2) < freeSpace)) {
                endFlip -= 2;
            }
            if (endFlip < startFlip) {
                float height = finder.verticalFlips.get(startFlip) - finder.verticalFlips.get(endFlip);

                directContent.saveState();
                directContent.rectangle(0, yPosition - height, pageSizeToImport.getWidth(), height);
                directContent.clip();
                directContent.newPath();

                directContent.addTemplate(importedPage, 0, yPosition - (finder.verticalFlips.get(startFlip) - pageSizeToImport.getBottom()));

                directContent.restoreState();
                yPosition -= height + gap;
                startFlip = endFlip - 1;
            } else if (!first) {
                throw new IllegalArgumentException(String.format("Page %s content sections too large.", page));
            }
            first = false;
        }
}

I have been searching the web, reading the api's for itext7 and still can't turn this to make it work. Can't find any replacement for PdfImportedPage and PdfContentByte.

I have listed my code up, my main question is what to use in replacement for PdfImportedPage and PdfContentByte