docs: public synchronized List<PrioritizedSplitRunner> destroy()
      {
          destroyed = true;
  
          ImmutableList.Builder<PrioritizedSplitRunner> builder = ImmutableList.builder();
          builder.addAll(runningIntermediateSplits);
          builder.addAll(runningLeafSplits);
          builder.addAll(queuedLeafSplits);
          runningIntermediateSplits.clear();
          runningLeafSplits.clear();
          queuedLeafSplits.clear();
          return builder.build();
      }