queue.setUrl(url);
        assertEquals(url, queue.getUrl());

        queue.setUrl(null);
        assertNull(queue.getUrl());
    }

    public void test_metaDataGetterSetter() {
        // Test metadata getter/setter
        UrlQueueImpl<Long> queue = new UrlQueueImpl<>();

        String metaData = "{\"key\":\"value\"}";
        queue.setMetaData(metaData);