/usr/lib/python3/dist-packages/plainbox/impl/providers/stubbox/bin/stub_package_list is in python3-plainbox 0.5.3-2.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 | #!/bin/sh
echo "name: checkbox"
echo ""
|