docs: public static File file(File directory, String... names) {
  		Assert.notNull(directory, "directorydirectory must not be null");
  		if (ArrayUtil.isEmpty(names)) {
  			return directory;
  		}
  
  		File file = directory;
  		for (String name : names) {
  			if (null != name) {
  				file = file(file, name);
  			}
  		}
  		return file;
  	}