public class PublishingInMemoryFeatureStore extends InMemoryFeatureStore {

    @Override
    public <T extends VersionedData> void upsert(VersionedDataKind<T> kind, T item) {
        String key = item.getKey();
        T current = get(kind, key);
        super.upsert(kind, item);
        T updated = get(kind, key);
        if (!Objects.equals(current, updated)) {
            // do publish
        }
    }
}