code: @Override
      protected void _to(ObjectOutput out) throws IOException {
          final int size = protoNodes.size();
          out.writeInt(size);
          int i = 0;
          for (String protoNode : protoNodes) {
              out.writeObject(protoNode);
              out.writeInt(nodeTermIndex.get(i).intValue());
              i++;
          }
  
          out.writeObject(remappedNodes);
          out.writeObject(equivalences);
      }
docs: {@inheritDoc}