code: public static LottieTask<LottieComposition> fromUrl(final Context context, final String url) {
      String urlCacheKey = "url_" + url;
      return cache(urlCacheKey, new Callable<LottieResult<LottieComposition>>() {
        @Override public LottieResult<LottieComposition> call() {
          return NetworkFetcher.fetchSync(context, url);
        }
      });
    }
docs: Fetch an animation from an http url. Once it is downloaded once, Lottie will cache the file to disk for
  future use. Because of this, you may call `fromUrl` ahead of time to warm the cache if you think you
  might need an animation in the future.