/usr/src/linux-headers-4.15.0-46-lowlatency/certs is in linux-headers-4.15.0-46-lowlatency 4.15.0-46.49~16.04.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/src/linux-headers-4.15.0-46-lowlatency/../linux-headers-4.15.0-46/certs