Paging for "Get Ticket Activities" is non-standard

I was recently using the “Get Ticket Activities” V2 API to fetch all the activities for a ticket but not all activities were being returned. Upon investigation, the paging mechanism for this API does not follow the documented mechanism for API V2 that uses “per_page” and “page” in the URI, based on a value returned in the response header.

It turns out that this API returns a value named “next_page_url” in the request body, whose value looks like this:

This is different from the documented paging mechanism for V2 that returns a value named “link” in the response header, whose value looks like this:; rel=“next”

Is this the expected behavior for “Get Ticket Activities” and if so, is this documented anywhere. It does ot appear in the Paging topic for V2. Additionally, are there other listing-type APIs that may not follow the documented standard and so unreturned objects may not be discovered because they don’t page the same.