/usr/share/doc/libavahi-ui-gtk3-0/changelog.Debian.gz is in libavahi-ui-gtk3-0 0.6.32~rc+dfsg-1ubuntu2.3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libavahi-ui-gtk3-0/../libavahi-common-data/changelog.Debian.gz