@Override
    public V obtainHandle(final K key, final Supplier<V> supplier) {
        return cached.getOrDefault(key, supplier.get());
    }
@Test
    public void obtainHandle() {
        assert null == commonHandleCache.obtainHandle(MOCK_KEY);
        cachedMockMap.put(MOCK_KEY, MOCK_VALUE);
        assert MOCK_VALUE.equals(commonHandleCache.obtainHandle(MOCK_KEY));
    }