/usr/lib/x86_64-linux-gnu/libnxml.so is in libnxml0-dev 0.18.3-6.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libnxml.so.0.18.3
/usr/lib/x86_64-linux-gnu/libnxml.so.0.18.3