docs: protected void insertNewKeyValueAt(int i, short key, Container value) {
      extendArray(1);
      System.arraycopy(keys, i, keys, i + 1, size - i);
      keys[i] = key;
      System.arraycopy(values, i, values, i + 1, size - i);
      values[i] = value;
      size++;
    }