Invalid signature when building jar via packageUberJarForCurrentOS

I'm currently trying to migrate one of my older JavaFX projects to compose-jb desktop. To make the new application compatible with the old one, i want to continue distributing fat jars.

Right now, i'm able to build the fat jar but whenever i try to run it via jar -jar ... it just fails with the following error:

Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.SecurityException: Invalid signature file digest for Manifest main attributes
    at java.base/sun.security.util.SignatureFileVerifier.processImpl(SignatureFileVerifier.java:317)
    at java.base/sun.security.util.SignatureFileVerifier.process(SignatureFileVerifier.java:259)
    at java.base/java.util.jar.JarVerifier.processEntry(JarVerifier.java:273)
    at java.base/java.util.jar.JarVerifier.update(JarVerifier.java:230)
    at java.base/java.util.jar.JarFile.initializeVerifier(JarFile.java:759)
    at java.base/java.util.jar.JarFile.ensureInitialization(JarFile.java:1038)
    at java.base/java.util.jar.JavaUtilJarAccessImpl.ensureInitialization(JavaUtilJarAccessImpl.java:69)
    at java.base/jdk.internal.loader.URLClassPath$JarLoader$2.getManifest(URLClassPath.java:870)
    at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:786)
    at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:698)
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:621)
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:579)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
    at java.base/java.lang.Class.forName0(Native Method)
    at java.base/java.lang.Class.forName(Class.java:398)
    at java.base/sun.launcher.LauncherHelper.loadMainClass(LauncherHelper.java:760)
    at java.base/sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:655)

I've read that this is because some jars i depend on are signed, so i tried to add the following lines to exclude signature files:

tasks {
    withType<Jar> {
        exclude("META-INF/*.RSA", "META-INF/*.SF", "META-INF/*.DSA")
    }
}

However, it seems like compose-jb still includes those files in the fat jar:

I would really appreciate any advice on how to fix this.

Source: https://github.com/DarkAtra/bfme2-patcher/blob/ceb801bdd0304d5b863909616b53aaf7d96c5064/build.gradle.kts#L58-L62

GH Post: https://github.com/JetBrains/compose-jb/discussions/2290

Solution

Seems like i was using the wrong Jar type in withType<Jar>.

After changing it to org.gradle.jvm.tasks.Jar it correctly excluded all signature related files from the uber jar.

tasks {
    withType<org.gradle.jvm.tasks.Jar> {
        exclude("META-INF/*.RSA", "META-INF/*.SF", "META-INF/*.DSA")
    }
}