I posted a bug on GitHub, but am not too sure if those are checked or not:
Even though I don't specify credentials, they appear to being set to an empty array , which isn't nil, and so the check in the s3 plugin always skips using environment variables:
I think I know how to code around this:
but I don't know if my case isn't working because of a combination of java version and OS, and would rather not mess with something that I'm not familiar enough with. Also, I think the problem might be with the validation routine or the expectation that an Array can have nil as a default.