Auto detection of installed toolchains for Github Action setup-java

[meiao]

When running a Java project in Github Actions it is common to use Github's setup-java action to install each version of Java. They are (currently) installed to /opt/hostedtoolcache/jdk/{jdk version}/x64 which is not in the auto detect path for Gradle's toolchain.

So when a build uses toolchains, it will not use the JDK installed by setup-java and will either try to find the required JDKs in the system or download as needed.

Expected Behavior

JDKs installed by setup-java are auto detected.

Current Behavior

Toolchain auto detection does not detect JDKs installed by setup-java.

Context

This affected a project that builds with Java 8 but creates Javadoc with Java 11. Even though we were installing the latest version of 11, the generated Javadoc had a JS resource that was older than the one from 11.0.14.

To investigate why that was happening, I created this repo https://github.com/meiao/expert-octo-toolchain-test/ which has longer description and a workaround.

It would also be nice to have a flag to disable auto detect in places other than the path used by setup-java so this way it would be harder to use an unexpected JDK.

[tbroyer]

Isn't this a duplicate of #14903?

And you can use org.gradle.java.installations.auto-detect and org.gradle.java.installations.paths (or org.gradle.java.installations.fromEnv) properties to control Gradle's behavior: https://docs.gradle.org/current/userguide/toolchains.html

[meiao]

It is. But in here there is also a nod to using a possibly maliciously installed Java environment.

I've used those parameters, and the linked repo has instructions on how to use those.

Anyway, closing as dupe.