/usr/share/doc/libxmltooling-dev/NOTICE.txt is in libxmltooling-dev 1.5.3-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libxmltooling-dev/../libxmltooling6/NOTICE.txt
/usr/share/doc/libxmltooling-dev/../libxmltooling6/NOTICE.txt