<K, V> Maplet<K, V> createMaplet(
    String storageName, Externalizer<K> keyExternalizer, Externalizer<V> valueExternalizer
  );
<K, V> Maplet<K, V> createMaplet(
    String storageName, Externalizer<K> keyExternalizer, Externalizer<V> valueExternalizer
  )