RE: Upgrade to Credentials 2.1.0+ API for populating credentials drop-down

[Stephen Connolly]

There are probably 30+ plugin authors who have just got lovely shiny new improvement JIRA tickets for "Upgrade to Credentials 2.1.0+ API for populating credentials drop-down"

These tickets are just a hint. If you don't want to act on the hint, that is your business as a plugin maintainer.

In any case for the next week or two I will be non-grumpy if people ask for reviews or assistance with updating their plugins to the new API, so I suggest that you at least create a PR for the update.

You may want to hold off merging such PRs until we've had two weeks soak of credentials 2.1.0 (though I believe this should be as stable as 2.0.7)

If you have a plugin using the credentials API and I didn't create a JIRA for you, do not feel bad, I may just have missed your usage when searching GitHub for plugins using the `withEmptySelection` or `withMatching` methods

When you are updating your plugins you may want to future-proof yourself for https://issues.jenkins-ci.org/browse/JENKINS-35081 by switching to Tasks.getDefaultAuthenticationOf(job) rather than using ACL.SYSTEM

Have fun!

-Stephen