I don't see how to fix this but the "Verify no unstaged changes" is failing. I'm working on Windows but usually it doesn't matter.

It is caused by the difference between LF (Ubuntu) and CRLF (Windows). I also faced this problem before.
I solved it by replacing the dist with files built on linux machine, we can upload the dist file to workflow by actions/upload-artifact:

https://github.com/KengoTODA/setup-java/blob/aae89bdd784d68e53c1bda327075e7af68d50ac5/.github/workflows/build.yml#L31-L34

Note about the context of current key naming:

1. First, it followed the actions/cache documentation: ${process.env['RUNNER_OS']}-${packageManager.id}-${hash}
2. Second, get reviewed and suggested to add a prefix, so
3. Added a prefix and now it's ${CACHE_KEY_PREFIX}-${process.env['RUNNER_OS']}-${packageManager.id}-${hash}

Hi @KengoTODA, I found another way , to correct the file, I'm creating a workflow where I execute the build and then have a task to commit the changed file directly on my repository, see here for example

Concerning the notion of prefix I'm not sure to really understand the reason behind that. Does it means that the provided examples in actions/cache are wrong ? Their is no explanation behind that change in the comment.
What I'm doing here is just moving this prefix after the operating system which quite more common in the community as most of the people take example on that same page I referenced earlier.

Does it means that the provided examples in actions/cache are wrong ?

It's not wrong. And there is no strict official rule to design the cache key... what we need is just grab how actions/cache matches a cache key and design optimized key and restore keys. So I just shared the context of current change... repository owner will judge how the key should be designed.