Support reverse order in `pageRanges` param in `/chromium/pdf` REST API

A problem I need to generated PDF file with footer only on last page but the only working solution which I found has drawback - empty page on the end of the document. In this case I can just drop last page to get desired document.

Solution Support reverse order indices in pageRanges param in /chromium/pdf REST API like in following console tools.

pdftk:

You can reference page numbers in reverse order by prefixing them with the letter r. For example, page r1 is the last page of the document, r2 is the next-to-last page of the document, and rend is the first page of the document. You can use this prefix in ranges, too, for example r3-r1 is the last three pages of a PDF.

qpdf:

A number preceded by r counts from the end, so r1 is the last page, r2 is the second-to-last page, etc.

Alternatives Use console tools like pdftk or qpdf to drop unwanted pages after generating PDF.