/usr/share/doc/libfastjetplugins-dev/changelog.Debian.gz is in libfastjetplugins-dev 3.0.6+dfsg-3build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libfastjetplugins-dev/../libfastjet0v5/changelog.Debian.gz