create fat jar with gradle kotlin dsl

build.gradle.kts

tasks.create<Jar>("fatJar") {
    appendix = "fat"
    setDuplicatesStrategy(DuplicatesStrategy.FAIL)
    manifest {
        attributes(mapOf("Main-Class" to "Main")) // replace it with your own
    }
    val sourceMain = java.sourceSets["main"]
    from(sourceMain.output)

    configurations.runtimeClasspath.filter {
        it.name.endsWith(".jar")
    }.forEach { jar ->
        from(zipTree(jar))
    }
}

not worked for me in case smallrye microprofile...

I found, that this one is working as expected:

tasks {
  register("fatJar", Jar::class.java) {
    archiveClassifier.set("all")
    duplicatesStrategy = DuplicatesStrategy.EXCLUDE
    manifest {
      attributes("Main-Class" to mainClass)
    }
    from(configurations.runtimeClasspath.get()
        .onEach { println("add from dependencies: ${it.name}") }
        .map { if (it.isDirectory) it else zipTree(it) })
    val sourcesMain = sourceSets.main.get()
    sourcesMain.allSource.forEach { println("add from sources: ${it.name}") }
    from(sourcesMain.output)
  }
}