code: public static File directory(String fileName) {
  		Validate.notNull(fileName);
  		Validate.notEmpty(fileName);
  		return Validate.directory(new File(fileName));
  	}
docs: Checks if there is an existing file with the given name and this file is a directory.<br>
  This method assumes that the given String contains the complete file path.
  @param fileName The file name (+path) to validate.
  @return A file reference for the given file name.
  @throws ParameterException if such a file does not exist or is not a directory.