code: function(idsResult) {
        if (_.isEmpty(idsResult) && _.isEmpty(this.data.privateCollection.getTrackedIds())) {
          return { skipObjectRetrieval: true, forceFetchedEvent: true };
        } else {
          return idsResult;
        }
      }
docs: Skip retrieving objects if new ids list is empty and existing ids list is empty.
  @method __skipRetrieveOnEmptyTrackedIdsAndNewIds
  @param idsResult {Array|Object}
  @return {Array|Object} either the original idsResult
  or { skipObjectRetrieval: true, forceFetchedEvent: true } if both the ids retrieved
  and the current ids are empty.
  @private