/usr/share/doc/libjson-glib-1.0-0-dbg/changelog.Debian.gz is in libjson-glib-1.0-0-dbg 0.16.2-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libjson-glib-1.0-0-dbg/../libjson-glib-1.0-0/changelog.Debian.gz