Gradle does not seem to use $JAVA_HOME

[sei-eschwartz]

Extension Name: vscode-gradle
Extension Version: 3.16.4
OS Version: Ubuntu 22.04.5 LTS
VSCode version: 1.95.2

Describe the bug

I have the JAVA_HOME variable set to the Temurin 21 JDK: /usr/lib/jvm/temurin-21-jdk-amd64. I expected that Gradle would do something sensible like use this as the default unless I configure otherwise.

But this does not seem to be what happens.

If I create a dummy build.gradle file containing:

task printJavaHome {
    doLast {
        println "Java Home: ${System.getProperty('java.home')}"
    }
}

And then I run this from VS code, I get:

> Task :printJavaHome
Java Home: /home/ed/.vscode/extensions/redhat.java-1.36.0-linux-x64/jre/17.0.13-linux-x86_64

Not what I was expecting!

Even if I set "java.jdt.ls.java.home": "/usr/lib/jvm/temurin-21-jdk-amd64", this is ignored. It is only if I set "java.import.gradle.java.home": "/usr/lib/jvm/temurin-21-jdk-amd64", that my JDK is used.

To Reproduce
Set $JAVA_HOME, create dummy gradle project as above.

Expected behavior
I expected $JAVA_HOME to be used as a reasonable default.

Output from "Gradle for Java"
You can find this by clicking on the "Output" panel, then selecting the "Gradle for Java" channel from the dropdown.

[info] [gradle-server] Gradle Server started, listening on 45455
[info] Gradle client connected to server
[info] Java Home: /home/ed/.vscode/extensions/redhat.java-1.36.0-linux-x64/jre/17.0.13-linux-x86_64
[info] JVM Args: --add-opens=java.base/java.util=ALL-UNNAMED,--add-opens=java.base/java.lang=ALL-UNNAMED,--add-opens=java.base/java.lang.invoke=ALL-UNNAMED,--add-opens=java.prefs/java.util.prefs=ALL-UNNAMED,--add-opens=java.base/java.nio.charset=ALL-UNNAMED,--add-opens=java.base/java.net=ALL-UNNAMED,--add-opens=java.base/java.util.concurrent.atomic=ALL-UNNAMED,-XX:MaxMetaspaceSize=384m,-XX:+HeapDumpOnOutOfMemoryError,-Xms256m,-Xmx512m,-Dfile.encoding=UTF-8,-Duser.country=US,-Duser.language=en,-Duser.variant
[info] Gradle User Home: /home/ed/.gradle
[info] Gradle Version: 8.8
[info] Deprecated Gradle features were used in this build, making it incompatible with Gradle 9.0.

You can use '--warning-mode all' to show the individual deprecation warnings and determine if they come from your own scripts or plugins.

For more on this, please refer to https://docs.gradle.org/8.8/userguide/command_line_interface.html#sec:command_line_warnings in the Gradle documentation.

CONFIGURE SUCCESSFUL in 2s
[info] Found 18 tasks

Does the bug still exist if you disable all other extensions?
If I don't install Language Server for Java, I get a Java 17 JDK by default, which is still unexpected. If I install Language Server for Java, I get the same one as above.