docs: public AggregatorFactory getMergingFactory(AggregatorFactory other) throws AggregatorFactoryNotMergeableException
    {
      final AggregatorFactory combiningFactory = this.getCombiningFactory();
      if (other.getName().equals(this.getName()) && combiningFactory.equals(other.getCombiningFactory())) {
        return combiningFactory;
      } else {
        throw new AggregatorFactoryNotMergeableException(this, other);
      }
    }