@Override
    public long decrementAndGet(K key) {
        return complete(asyncCounterMap.decrementAndGet(key));
    }
@Test
    public void testDecrementAndGet() {
        atomicCounterMap.put(KEY1, VALUE1);
        Long afterIncrement = atomicCounterMap.decrementAndGet(KEY1);
        assertThat(afterIncrement, is(VALUE1 - 1));
    }