anchor.diff:          String resultSelector
         }) {
       return new Future.sync(() {
  -      var query = new _Query(projectId)
  +      var query = new _Query()
             ..['ifMetagenerationMatch'] = ifMetagenerationMatch
             ..['ifMetagenerationNotMatch'] = ifMetagenerationNotMatch
             ..['projection'] = projection
  
positive.code:     if (selector != "*") {
        fields += "($selector)";
      }
      var query = new _Query(projectId)
          ..['maxResults'] = (maxResults >= 0) ? maxResults : null
          ..['projection'] = projection
          ..['fields'] = fields;
  
negative.code:         int ifMetagenerationNotMatch
        }) {
      return new Future.sync(() {
        var query = new _Query()
            ..['ifMetagenerationMatch'] = ifMetagenerationMatch
            ..['ifMetagenerationNotMatch'] = ifMetagenerationNotMatch;
  
  