It would be nice to have a flatpak of JabRef. The GNOME Software Center as well as Linux Mint Software Manager mintinstall do support flatpaks now.
The flatpak can be uploaded to https://flathub.org/
Reason for this feature is:
The Ubuntus LTS version 16.04 still has JabRef 2.10 in it’s repositories. Having a flatpak version users could install and use the newest JabRef version very easily now and getting updates for JabRef (without having to manually download the latest jar version and create manually a menu entry for the downloaded jar file).