Using GroovySample extension point

[jglick]

Downstream of jenkinsci/workflow-cps-plugin#350. Migrated those scripts in examples/ which were self-contained (do not require manual preconfiguration, such as registry credentials or a PVC); were reasonably representative (covering some major use cases); and are compatible with PodSecurityPolicy (so, no Docker).

[Vlatombe]

Looks ok though I feel uneasy with the writeFile gym.

[jglick]

I feel uneasy with … writeFile

It is not great but the alternatives I could think of had worse problems:

• checking out some repository on GitHub that could change or be deleted at any time
• using master of some subdirectory of this repo, which could also change out of synch with the plugin JAR
• using a tag of this repo, which would be tricky to check out and hard to review changes in
• using the git-server plugin to serve content
• publishing images to Docker Hub which bundle sources

At least the current approach is 100% self-contained. For purposes of PR review, it would be possible to load the external files from a classpath resource, but the sample script shown to a user would be the same.

[Vlatombe]

Looks great,