}

  private @Nullable Object[] requireElements() {
    return requireNonNull(elements);
  }

  @SuppressWarnings("unchecked")
  private E element(int i) {
    return (E) requireElements()[i];
  }

  private int entry(int i) {
    return requireEntries()[i];
  }

  private void setElement(int i, E value) {
    requireElements()[i] = value;
  }