code: public void addTranslation (String oldname, String newname)
      {
          if (_translations == null) {
              _translations = Maps.newHashMap();
          }
          _translations.put(oldname, newname);
      }
docs: Configures this object input stream with a mapping from an old class name to a new
  one. Serialized instances of the old class name will use the new class name when
  unserializing.