FutureTask with CompletionStage

future.groovy

import java.util.concurrent.CompletableFuture
import java.util.concurrent.FutureTask
import java.util.concurrent.Callable

def task = new FutureTask({
    println "runAsync: ${Thread.currentThread()}"
    def i = 0
    for (; i < 5; ++i) {
        println "count: $i"
        Thread.sleep(200)
    }
    return i - 1
} as Callable<Integer>)
def future = CompletableFuture.supplyAsync { task.run(); task.get() }
        .thenAccept { println "completed with $it" }
        .exceptionally { println "exception: $it" }

Thread.sleep(500)
task.cancel(true)

println "await"
future.get()
println "finished"