public static String fromLowerLetter(String str) {
    if (str.isEmpty()) return "";
    if (str.length() == 1) return StringUtil.toLowerCase(str);
    char c = Character.toLowerCase(str.charAt(0));
    if (c == str.charAt(0)) return str;
    return c + str.substring(1);
  }
public static String fromLowerLetter(String str)