@Override
  public IndexBlockEncoding getIndexBlockEncoding() {
    return IndexBlockEncoding.NONE;
  }
Writes this chunk into the given output stream in the root block index format. This format is
similar to the {@link HFile} version 1 block index format, except that we store on-disk size of
the block instead of its uncompressed size.
@param out the data output stream to write the block index to. Typically a stream writing into
           an {@link HFile} block.
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/NoOpIndexBlockEncoder.java