Created attachment 170385 [details]
A screenshot of the de-facto standard annotation icons which are not supported

SUMMARY
Okular does not display the Check, Star, RightArrow, RightPointer, UpArrow, UpLeftArrow, and CrossHairs icons

STEPS TO REPRODUCE
1. Open http://mirrors.ctan.org/macros/latex/contrib/pdfcomment/doc/pdfcomment.pdf
2. Scroll to section 1.2.4

OBSERVED RESULT
Of the non-mandatory icons, only Circle and Cross are shown (though the others are clickable - so they are simply invisible).

EXPECTED RESULT
The other icons should also be supported, or at least a fallback icon should be displayed.

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION
- Chromium simply displays them with the Comment icon.
- PDF.js displays them as "[Star Annotation]" etc.