How to automatically save at shutdown and restore Okular / KDE sessions in Ubuntu?

When I reopen Okular, I want to have the same windows / tabs as when I last closed it, usually at system shutdown / startup.

Is that possible in Ubuntu (not Kubuntu, running the standard desktop). 15.10 here, but all versions appreciated.

There seems to be a way to save the global KDE session, so that may be the way to go: https://bugs.kde.org/show_bug.cgi?id=300985