code: private static <K, V> List<KeyValue<K, List<V>>> multimapToList(
        Marshaller<K> keyMarshaller, ListMultimap<Bytes, V> in) {
      List<Bytes> keys = Ordering.natural().sortedCopy(in.keySet());
      ImmutableList.Builder<KeyValue<K, List<V>>> out = ImmutableList.builder();
      for (Bytes keyBytes : keys) {
        K key = keyMarshaller.fromBytes(ByteBuffer.wrap(keyBytes.bytes));
        out.add(KeyValue.of(key, in.get(keyBytes)));
      }
      return out.build();
    }
docs: Also turns the keys back from Bytes into K.