/usr/lib/x86_64-linux-gnu/libjson-c.so is in libjson-c-dev 0.12.1-1.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /lib/x86_64-linux-gnu/libjson-c.so.3
/lib/x86_64-linux-gnu/libjson-c.so.3