public static List<Container> listOrNull(Container container)   {
        return container != null ? List.of(container) : null;
    }
@Test
    public void testListOrNull()    {
        assertThat(ContainerUtils.listOrNull(null), is(nullValue()));
        assertThat(ContainerUtils.listOrNull(new ContainerBuilder().withName("my-container").build()).size(), is(1));
    }