/usr/lib/x86_64-linux-gnu/roboptim-core/roboptim-core-plugin-dummy-laststate.so.2 is in libroboptim-core2-plugin-base 2.0-7.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/roboptim-core/roboptim-core-plugin-dummy-laststate.so.2.0.0