/usr/share/doc/libunity-settings-daemon-dev/AUTHORS is in libunity-settings-daemon-dev 15.04.1+16.04.20160209-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libunity-settings-daemon-dev/../libunity-settings-daemon1/AUTHORS