In the example for folder children included with the AtomPub bindings for CMIS, I noticed a weird thing just before the end of the document:
Now Atom’s liberal content model allows various kinds of foreign markup. However, Atom very carefully prevents any foreign markup from occurring at the end of a list of entries. In other words, it is illegal to put anything in a feed document after the first entry besides another entry element.
That means if you want to indicate that this feed document is the last in a series of pages containing the children of a folder, that foreign markup has to come before the first entry in the feed document.
Alternatively, just use Atom paging and archiving and be done with it. In fact, AtomPub has its own paging, if that meets the needs of CMIS (no reason why it can’t).