docs: public static String[] split(String input, String regex) {
      if (input == null) {
        return null;
      }
      String[] arr = input.split(regex);
      List<String> results = new ArrayList<>(arr.length);
      for (String a : arr) {
        if (!a.trim().isEmpty()) {
          results.add(a);
        }
      }
      return results.toArray(new String[0]);
    }