public Chooser(K uniqueKey) {
        this(uniqueKey, new ArrayList<>());
    }
@Test
    void testChooser() {
        //Test the correctness of Chooser, the weight of the final selected instance must be greater than 0
        List<Instance> hosts = getInstanceList();
        Instance target = getRandomInstance(hosts);
        assertTrue(hosts.contains(target) && target.getWeight() > 0);
    }