code: private InputStream openFooterStream() {
      contentChannelPosition = currentPosition;
      int offset = Math.toIntExact(currentPosition - (size - footerContent.length));
      int length = footerContent.length - offset;
      logger.atFine().log(
          "Opened stream (prefetched footer) from %s position for '%s'",
          currentPosition, resourceIdString);
      return new ByteArrayInputStream(footerContent, offset, length);
    }
docs: Opens the underlying stream from {@link #footerContent}, sets its position to the {@link
  #currentPosition}.