public void restore() throws IOException {
      SeekableByteChannel channel = channelAndPosition.getChannel();
      originalHeader.rewind();
      channelAndPosition.rewind();
      assertEquals(originalHeader.capacity(), channel.write(originalHeader));
    }
Enables writing and rewriting portions of the file backing an {@link HFileBlock}.
hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileBlockHeaderCorruption.java