shadowJar task with minimize() doesn't use gradle toolchain.

[VasilisManol]

Expected and Results

call shadowJar task with minimize() without errors.

Related environent and versions

Gradle 8.6
shadow 8.3.5

Installed JDKs
openjdk 8 - default
openjdk 21

Reproduction steps

• Use jdk 8 as default
• Install jdk 21
• Create a gradle project with build.gradle.kts:

plugins {
    id("java")
    id("com.gradleup.shadow") version ("8.3.5")
}

java {
    toolchain {
        languageVersion.set(JavaLanguageVersion.of(21))
    }
}

configure<JavaPluginExtension> {
    sourceCompatibility = JavaVersion.VERSION_1_8
    targetCompatibility = JavaVersion.VERSION_21
}

repositories {
    mavenCentral()
    mavenLocal()
}

dependencies {
....
}

tasks.named<com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar>("shadowJar") {
    exclude("META-INF", "META-INF/**")
    minimize()
    archiveClassifier.set("")
    isZip64 = true
}

tasks {
    build {
        dependsOn(shadowJar)
    }
}

• Build e.g. ./gradlew build
  Then the following error occurs:

  Execution failed for task ':shadowJar'.
> org/vafer/jdependency/Clazzpath has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0

If minimize() is commented out it builds as expected.

Anything else?

This error looks related with #814 but maybe not exactly the same. When switching to jdk21 as default jdk, minimize() doesn't give any error.

[Goooler]

@VasilisManol This looks unrelated to Shadow, can you try out deleting

configure<JavaPluginExtension> {
    sourceCompatibility = JavaVersion.VERSION_1_8
    targetCompatibility = JavaVersion.VERSION_21
}

[VasilisManol]

@Goooler I get the same even when I comment out that part. Even in that case, it builds without errors, if I just comment out the minimize(). Can you explain why you think it is unrelated to Shadow? For me, the fact that it fails only if I call minimize() but it works otherwise, points to Shadow and actually the implementation of the minimize() feature.

[Goooler]

It's related to sourceCompatibility = JavaVersion.VERSION_1_8, org/vafer/jdependency/Clazzpath requires Java 11 to run, which minimize depends on, but you pinned Java 8 here cause it failed.

[VasilisManol]

I see your point but then it should work with your suggestion. I think the issue is that Shadow doesn't use the toolchain defined in

 java {
    toolchain {
        languageVersion.set(JavaLanguageVersion.of(21))
    }
}

As I wrote my default java on the system is java 8 and this is what Shadow uses. If I set default java to 21 then it works.

[Goooler]

ShadowJar extends org.gradle.jvm.tasks.Jar, I don't see how to configure and use toolchain in that, need more time to investigate...