/usr/share/doc/libsaml2-dev/NOTICE.txt is in libsaml2-dev 2.5.3-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libsaml2-dev/../libsaml8/NOTICE.txt
/usr/share/doc/libsaml2-dev/../libsaml8/NOTICE.txt