public static Resource _find(Folder parent, String[] arr, int i, boolean invalidateCache)
     throws IOException, com.ettrema.httpclient.HttpException, NotAuthorizedException,
         BadRequestException {
   String childName = arr[i];
   if (invalidateCache) {
     parent.flush();
   }
   Resource child = parent.child(childName);
   if (i == arr.length - 1) {
     return child;
   } else {
     if (child instanceof Folder) {
       return _find((Folder) child, arr, i + 1, invalidateCache);
     } else {
       return null;
     }
   }
 }