code: @Override
    public String format(int index)
    {
      --index; // lists index value starts with 1
      int charsCount = index / dictionary.length() + 1;
      index = index % dictionary.length();
      char c = dictionary.charAt(index);
      StringBuilder sb = new StringBuilder();
      for(int i = 0; i < charsCount; ++i) {
        sb.append(c);
      }
      return sb.toString();
    }
docs: Format index as upper case string. Transform index into a upper case string following next rules:
  <ul>
  <li>be dictionary the set of English upper case characters,
  <li>if index is smaller that dictionary length uses index directly to extract the character and return it,
  <li>divide index by dictionary length,
  <li>be chars count the quotient plus one,
  <li>be index equals remainder,
  <li>extract char from dictionary using index and return it repeated chars count times.
  </ul>
  
  @param index index value.
  @return formatted index.