In the README file, https://github.com/actions/setup-java#v2-vs-v1 discusses V1 vs V2. It would be good to also mention v3, which is used later in the README. It also might be good to move that section later in the README.

The section on Supported version syntax suggests that only 8, 11, 16, and 17 are permitted. If those are examples rather than an exhaustive list, please state that explicitly.

Thanks.