private static String getMD5(String input, int maxLength) {
    MessageDigest md;
    try {
      md = MessageDigest.getInstance("MD5");
    } catch (NoSuchAlgorithmException e) {
      // For some reason, md5 doesn't exist, return a substring.
      // This should never happen.
      return input.substring(0, maxLength);
    }
    byte[] messageDigest = md.digest(input.getBytes());
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < messageDigest.length; i++) {
      byte b = messageDigest[i];
      sb.append(String.format("%02x", b));
    }
    return sb.toString();
  }
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