code: private static String [] decodePath(String s) {
      assert s.startsWith(KEY_PREFIX) && s.indexOf('/') >= 0 : "Attempting to decode non s3 key: " + s;
      s = s.substring(KEY_PREFIX_LEN);
      int dlm = s.indexOf('/');
      if(dlm < 0) return new String[]{s,null};
      String bucket = s.substring(0, dlm);
      String key = s.substring(dlm + 1);
      return new String[] { bucket, key };
    }
docs: Decompose S3 name into bucket name and key name
  
  @param s generic s3 path (e.g., "s3://bucketname/my/directory/file.ext")
  @return array of { bucket name, key }