private void putHeaderInt(int offset,
                            int value) {
    assert (0 <= offset && offset <= HeaderLayout.HEADER_SIZE - Integer.BYTES)
      : "header offset(=" + offset + ") must be in [0," + (HeaderLayout.HEADER_SIZE - Integer.BYTES) + "]";
    headerPage.rawPageBuffer().putInt(offset, value);
  }
private void putHeaderInt(int offset,
                            int value)