* symlink the files you like into /etc/apt/*
* create-gpgring.sh can create new files for trusted.gpg.d/ from public keys and should be preferred over apt-key add

Key sources:

* https://jenkins-ci.org/debian/jenkins-ci.org.key
* https://debian.lighttpd.net/jenkins-lighttpd.net.gpg
* `osc signkey` for OBS projects