public boolean isUnpacked() {
    final int headerSize = headerSize();
    final int expectedCapacity = headerSize + uncompressedSizeWithoutHeader;
    final int bufCapacity = bufWithoutChecksum.remaining();
    return bufCapacity == expectedCapacity || bufCapacity == expectedCapacity + headerSize;
  }
Return true when this block's buffer has been unpacked, false otherwise. Note this is a
calculated heuristic, not tracked attribute of the block.
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java