/usr/share/doc/libqt5gui5/changelog.Debian.gz is in libqt5gui5 5.5.1+dfsg-16ubuntu7.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libqt5gui5/../libqt5core5a/changelog.Debian.gz
/usr/share/doc/libqt5gui5/../libqt5core5a/changelog.Debian.gz