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