import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Executor;
import java.util.concurrent.ForkJoinPool;

public class CompletableFutureMain {

    public static void main(String[] args) {
        System.setProperty("java.util.concurrent.ForkJoinPool.common.parallelism", Integer.toString(1));
        System.out.println("Common pool parallelism: " + ForkJoinPool.getCommonPoolParallelism());

        Executor executor = new CompletableFuture<>().defaultExecutor();
        executor.execute(null);
        System.out.println("Expected NPE but got no-op");
    }

}