flatpak doesn't set XDG_DATA_DIRS

[Simen Endsjø]

It seems flatpak doesn't update XDG_DATA_DIRS, so installed 
applications doesn't
show in the desktop and have to be started manually using `flatpak 
run ...`.
Should the package set this? If not, what's the best practice in 
setting this?

       Note that the directories

       '/var/lib/flatpak/exports/share'
       '/home/simendsjo/.local/share/flatpak/exports/share'

       are not in the search path set by the XDG_DATA_DIRS 
       environment variable, so
       applications installed by Flatpak may not appear on your 
       desktop until the
       session is restarted.