docs: public static boolean isBlank(String string) {
          if (string == null || string.length() == 0)
              return true;
  
          int l = string.length();
          for (int i = 0; i < l; i++) {
              if (!StringUtil.isWhitespace(string.codePointAt(i)))
                  return false;
          }
          return true;
      }