I have 2 issues with this, and neither pertain to your code or is your fault. But since this cookbook metadata doesn't indicate any support for windows I don't think we should add support to a single resource like this. It really should be fully added to support windows. The other is the lack of testing for the java cert resource. We run the test CB which utilizes the java_cert resource but then the integration tests only verify that java installed correctly. This makes it difficult to know if your change actually works or not.

I'm not saying we shouldn't do this, just pointing that out and going to defer to others on what they may think.

Understandable; I can certainly add more explicit testing for java_certificate to address that concern.

I can also see if there's a more "neutral" way for the following without explicitly performing the platform check. Might be able to just tweak the regex.

normalized_stdout = cmd.stdout
normalized_stdout = normalized_stdout.gsub(/\r\n/, "\n") if platform?('windows')
keystore_cert = normalized_stdout.match(/^[-]+BEGIN.*END(\s|\w)+[-]+$/m).to_s

Then there's less of an implicit indicator that the cookbook "supports" Windows.