code: private static String[] toRealPath(Config config, String dotPath) throws ExpressionException {
  	dotPath = dotPath.trim();
  
  	while (dotPath.indexOf('.') == 0) {
  	    dotPath = dotPath.substring(1);
  	}
  	int len = -1;
  	while ((len = dotPath.length()) > 0 && dotPath.lastIndexOf('.') == len - 1) {
  	    dotPath = dotPath.substring(0, len - 2);
  	}
  	return CustomTagUtil.getFileNames(config, dotPath.replace('.', '/'));
      }
docs: translate a dot-notation path to a realpath
  
  @param dotPath
  @return realpath
  @throws ExpressionException