/usr/share/doc/libgdamm5.0-dev/AUTHORS is in libgdamm5.0-dev 4.99.11-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libgdamm5.0-dev/../libgdamm-5.0-13/AUTHORS
/usr/share/doc/libgdamm5.0-dev/../libgdamm-5.0-13/AUTHORS