/usr/lib/x86_64-linux-gnu/liblua5.1-cjson.so is in lua-cjson-dev 2.1.0+dfsg-2.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/liblua5.1-cjson.so.0.0.0
/usr/lib/x86_64-linux-gnu/liblua5.1-cjson.so.0.0.0