private File parentDir() {
    File file = cacheProvider.getCacheDir();
    if (file.isFile()) {
      file.delete();
    }
    if (!file.exists()) {
      file.mkdirs();
    }
    return file;
  }
Returns the cache file for the given url if it exists. Checks for both json and zip.
Returns null if neither exist.
lottie/src/main/java/com/airbnb/lottie/network/NetworkCache.java