@Override
    public long nextChunkId() {
      if (!hasNextChunkIdField()) {
        throw new IllegalStateException("Chunk doesn't have .nextChunkId field reserved at creation");
      }
      int nextChunkFieldOffset = offsetInBuffer + chunkLength - NEXT_CHUNK_ID_SIZE;
      return (long)INT64_OVER_BYTE_BUFFER.getVolatile(pageBuffer, nextChunkFieldOffset);
    }
@Override
    public long nextChunkId()