fail();
    } catch (IllegalArgumentException success) {
    } finally {
      joinPool(e);
    }
  }

  /** invokeAny(c) throws NPE if c has null elements */
  public void testInvokeAnyImpl_nullElement() throws Exception {
    ListeningExecutorService e = newDirectExecutorService();
    List<Callable<Integer>> l = new ArrayList<>();
    l.add(
        new Callable<Integer>() {
          @Override