@Override
  public void awaitTerminated() throws InterruptedException {
    doAction(Executable::awaitTerminated);
  }
@Test
  public void shouldJoinAll() throws Exception {
    // When:
    multiExecutable.awaitTerminated();

    // Then:
    final InOrder inOrder = Mockito.inOrder(executable1, executable2);
    inOrder.verify(executable1).awaitTerminated();
    inOrder.verify(executable2).awaitTerminated();
    inOrder.verifyNoMoreInteractions();
  }