@Override
    public boolean remove(String key) {
        repo.lock(key);
        try {
            return repo.remove(key) != null;
        } finally {
            repo.unlock(key);
        }
    }
@Test
    public void testRemove() throws Exception {
        // ADD key to remove
        assertTrue(repo.add(key01));
        assertTrue(repo.add(key02));
        assertEquals(2, cache.size());

        // CLEAR repo
        repo.clear();
        assertEquals(0, cache.size());
    }