This file is indexed.

/etc/apt/apt.conf.d/99update-notifier is in update-notifier-common 0.154.1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

1
DPkg::Post-Invoke {"if [ -d /var/lib/update-notifier ]; then touch /var/lib/update-notifier/dpkg-run-stamp; fi; if [ -e /var/lib/update-notifier/updates-available ]; then echo > /var/lib/update-notifier/updates-available; fi "; };