docs: public void clearAll() {
      final List<EncodedImage> old;
      synchronized (this) {
        old = new ArrayList<>(mMap.values());
        mMap.clear();
      }
      for (int i = 0; i < old.size(); i++) {
        EncodedImage encodedImage = old.get(i);
        if (encodedImage != null) {
          encodedImage.close();
        }
      }
    }