So, on Linux, there aren't that many good options for PDF viewers which have any kind of reasonable note-making/highlighting options which aren't both lousy and closed-source (e.g. FoxIt). Okular is an exception to this, but I've managed to lose hours of work because it won't (by default) directly merge notes and highlighting into the PDF file itself. I understand that the developers seem to view this as ideal (i.e. Okular won't alter the PDF file itself by default), but it is really non-ideal for any use case for me. Almost always if I'm highlighting on taking notes on a PDF file, it's because I'm going to share it with someone else, and 98% of the time that someone else doesn't use Okular. There really needs to be an option in Okular that allows one to say "save notes and highlighting &c." directly to the PDF. It doesn't even need to be the default option, just needs to be there (and I don't mean some weird workaround like "Save as" or whatever it is currently, but a real proper "when I press C-s, Okular saves my notes/highlighting to the PDF file" option.)
I suggest the closure of this bug as invalid. Okular can save annotations / reviews directly into the PDF file although this is not done automatically (I do not want it saving automatically) as being said in the manual, ************* Since Okular 0.15 you can also save annotations directly into PDF files. This feature is only available if Okular has been built with version 0.20 or later of Poppler rendering library. You can use File → Save As... to save the copy of PDF file with annotations. *************
Yeah, this is done anyway for next version.