/usr/share/doc/mariadb-plugin-oqgraph/changelog.Debian.gz is in mariadb-plugin-oqgraph 10.0.24-7.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/mariadb-plugin-oqgraph/../mariadb-client-core-10.0/changelog.Debian.gz