public static synchronized Map<Pair<String, String>, String> getChanged() {
        return CpeEcosystemCache.changed;
    }
@Test
    public void testGetChanged() {
        Pair<String, String> key = new Pair<>("apache", "zookeeper");
        Map<Pair<String, String>, String> map = new HashMap<>();
        map.put(key, "java");
        CpeEcosystemCache.setCache(map);

        Map<Pair<String, String>, String> result = CpeEcosystemCache.getChanged();
        assertTrue(result.isEmpty());

        CpeEcosystemCache.getEcosystem("apache", "zookeeper", "java");
        result = CpeEcosystemCache.getChanged();
        assertTrue(result.isEmpty());

        CpeEcosystemCache.getEcosystem("apache", "zookeeper", null);
        result = CpeEcosystemCache.getChanged();
        assertTrue(result.isEmpty());

        //zookeeper is already at multiple- no change
        CpeEcosystemCache.getEcosystem("apache", "zookeeper", "c++");
        result = CpeEcosystemCache.getChanged();
        assertFalse(result.isEmpty());
    }