docs: private byte[] toStorageJson() {
      final ByteArrayOutputStream output = new ByteArrayOutputStream(
          display_name.length() + tsuid.length() + 30);
      try {
        final JsonGenerator json = JSON.getFactory().createGenerator(output);
        
        json.writeStartObject();
        
        // we only need to write a small amount of information
        json.writeObjectField("displayName", display_name);
        json.writeObjectField("tsuid", tsuid);
        
        json.writeEndObject();
        json.close();
        
        // TODO zero copy?
        return output.toByteArray();
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }