@Override
    public long addAndGet(K key, long delta) {
        return complete(asyncCounterMap.addAndGet(key, delta));
    }
@Test
    public void testAddAndGet() {
        atomicCounterMap.put(KEY1, VALUE1);
        Long afterIncrement = atomicCounterMap.addAndGet(KEY1, DELTA1);
        assertThat(afterIncrement, is(VALUE1 + DELTA1));
    }