code: @Override
      protected void _to(ObjectOutput out) throws IOException {
          documentTable.writeExternal(out);
          namespaceTable.writeExternal(out);
          parameterTable.writeExternal(out);
          termTable.writeExternal(out);
          termParameterMapTable.writeExternal(out);
          statementTable.writeExternal(out);
          annotationDefinitionTable.writeExternal(out);
          annotationValueTable.writeExternal(out);
          statementAnnotationMapTable.writeExternal(out);
          protoNodeTable.writeExternal(out);
          protoEdgeTable.writeExternal(out);
      }
docs: {@inheritDoc}