docs: public static int lastIndexOfSeparator(String filePath) {
  		if (StrUtil.isNotEmpty(filePath)) {
  			int i = filePath.length();
  			char c;
  			while (--i >= 0) {
  				c = filePath.charAt(i);
  				if (CharUtil.isFileSeparator(c)) {
  					return i;
  				}
  			}
  		}
  		return -1;
  	}