public InternalCompletableFuture<Collection<UUID>> invoke() {
        doInvoke();
        return future;
    }
@Test
    public void testInvoke() {
        Node node = getNode(instance1);
        Collection<UUID> uuids = invokeOnStableClusterParallel(
                node.getNodeEngine(),
                NoOpOperation::new,
                0
        ).join();

        Collection<UUID> expectedUuids = getUuidsOfInstances(instance1, instance2, instance3);
        assertThat(uuids)
                .containsExactlyInAnyOrderElementsOf(expectedUuids);
    }