anchor.diff:          if(jsonData is List) {
             if(jsonData[0] == CLEAN_UNDEFINED){
               action = 'add';
  +            ensureId(jsonData[0], idgen);
             }
             else if(jsonData[1] == CLEAN_UNDEFINED){
               action = 'remove';
  
positive.code: 
  
    Future addAll(List<Map> data, String author) {
      cache.invalidate();
      num nextVersion;
      return _get_locks().then((_) => _maxVersion).then((version) {
  
negative.code: 
  MongoProvider mpClone(MongoProvider source){
  
    MongoProvider m = new MongoProvider.config(source.collection,
        source._collectionHistory, source._lock, source.cache, source.idgen);
    m._selectorList = new List.from(source._selectorList);
    m._sortParams = new Map.from(source._sortParams);
    m._limit = source._limit;
  