/usr/lib/x86_64-linux-gnu/tumbler-1/plugins/cache/tumbler-cache-plugin.so is in tumbler 0.1.24-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/tumbler-1/plugins/cache/tumbler-xdg-cache.so