code: @Override
      public void prepare(FeatureProvider provider)
      {
          super.prepare(provider);
  
          if (provider instanceof ExtractorListener)
          {
              addListener((ExtractorListener) provider);
          }
          if (provider instanceof ExtractorChecker)
          {
              checker = (ExtractorChecker) provider;
          }
      }
docs: /*
  ExtractorServices