https://bugzilla.redhat.com/show_bug.cgi?id=1534446
--- Comment #7 from Robert-André Mauchin zebob.m@gmail.com --- - I missed something:
%{_datadir}/appdata/*.appdata.xml
New guidelines say Appdata files must be installed in %{_datadir}/metainfo/ See https://fedoraproject.org/wiki/Packaging:AppData
Also the appdata file must be validated with appstream-util. See https://fedoraproject.org/wiki/Packaging:AppData#app-data-validate_usage