@Override
    public CompletionStage<V> putAsync(K key, V value) {
        return map.putAsync(key, value);
    }
@Test
    public void testPutAsync() throws Exception {
        map.put(42, "oldValue");

        Future<String> future = adapter.putAsync(42, "newValue").toCompletableFuture();
        String oldValue = future.get();

        assertEquals("oldValue", oldValue);
        assertEquals("newValue", map.get(42));
    }