It would be useful for actions/setup-java and to use the same repository cache mechanism used by actions/cache to cache JDKs. This appears to be possible since the addition of https://github.com/actions/toolkit/tree/main/packages/cache in May.

setup-java should still look up the JDK to use (as the JDK determined by a semver spec and other options can change over time, e.g. as new updates get published). Once a specific JDK is determined (e.g. a specific tar.gz or .zip file URI is identified as a key), we can check (and populate) the cache to reuse the actual file hierarchy created for that JDK within that repository's cache across workflow runs. This can likely significantly improve workflow execution times, and bandwidth consumption.