docs: private synchronized Producer<Void> getDecodedImagePrefetchSequence(
        Producer<CloseableReference<CloseableImage>> inputProducer) {
      if (!mCloseableImagePrefetchSequences.containsKey(inputProducer)) {
        SwallowResultProducer<CloseableReference<CloseableImage>> swallowResultProducer =
            mProducerFactory.newSwallowResultProducer(inputProducer);
        mCloseableImagePrefetchSequences.put(inputProducer, swallowResultProducer);
      }
      return mCloseableImagePrefetchSequences.get(inputProducer);
    }