Add Class-Path attribute to a jar manifest in Gradle

build.gradle.kts

// Add Class-Path to the existing "jar" task
tasks.jar {
    val classpath = configurations.runtimeClasspath
    // Input declaration is needed for the proper up-to-date checks
    inputs.files(classpath).withNormalizer(ClasspathNormalizer::class.java)
    manifest {
        attributes(
            "Class-Path" to classpath.map { cp -> cp.joinToString(" ") { it.absolutePath } }
        )
    }
}