/usr/share/cups/doc-root/robots.txt is in cups-server-common 2.2.7-1ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | #
# This file tells search engines not to index your CUPS server.
#
User-agent: *
Disallow: /
|