@Override
  public void setConf(Configuration conf) {
    this.conf = conf;
  }
Updates the current block to be the given {@link HFileBlock}. Seeks to the the first
key/value pair.
@param newBlock the block read by {@link HFileReaderImpl#readBlock}, it's a totally new block
                with new allocated {@link ByteBuff}, so if no further reference to this
                block, we should release it carefully.
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileReaderImpl.java