Because of https://hibernate.atlassian.net/browse/HHH-7370 -- i.e. when ORDER BY is simple and OFFSET is 0, there is no ROW_NUMBER at all.
In all other case, after my change ROW_NUMBER will use order by if only it was defined.
The original order by remains in place (if I deem it safe) so that the TOP in inner query can stay there (i don't know why it is there, but since it's already there, i did not want to remove it).