This file is indexed.

/usr/lib/x86_64-linux-gnu/libgdk-3.so is in libgtk-3-dev 3.18.9-1ubuntu3.

This file is owned by root:root, with mode 0o777.

It is a symlink to /usr/lib/x86_64-linux-gnu/libgdk-3.so.0.1800.9