code: @Override
      public ExecutorService executorService() {
          InternalEventPipeline pipeline = currentPipeline.get();
          if (pipeline != null) {
              return pipeline.executorService();
          }
          return fallback.executorService();
      }
docs: /*
  (non-Javadoc)
  
  @see org.jgrapes.core.internal.InternalEventPipeline#executorService()