code: public static boolean isEmptyDirectory(Resource res, ResourceFilter filter) {
  	if (res.isDirectory()) {
  	    Resource[] children = filter == null ? res.listResources() : res.listResources(filter);
  	    if (children == null || children.length == 0) return true;
  
  	    for (int i = 0; i < children.length; i++) {
  		if (children[i].isFile()) return false;
  		if (children[i].isDirectory() && !isEmptyDirectory(children[i], filter)) return false;
  	    }
  
  	}
  	return true;
      }
docs: return Boolean.True when directory is empty, Boolean.FALSE when directory s not empty and null if
  directory does not exists
  
  @param res
  @return