@Override
  public void appendMetaBlock(String metaBlockName, Writable content) {
    byte[] key = Bytes.toBytes(metaBlockName);
    int i;
    for (i = 0; i < metaNames.size(); ++i) {
      // stop when the current key is greater than our own
      byte[] cur = metaNames.get(i);
      if (Bytes.BYTES_RAWCOMPARATOR.compare(cur, 0, cur.length, key, 0, key.length) > 0) {
        break;
      }
    }
    metaNames.add(i, key);
    metaData.add(i, content);
  }
Add a meta block to the end of the file. Call before close(). Metadata blocks are expensive.
Fill one with a bunch of serialized data rather than do a metadata block per metadata instance.
If metadata is small, consider adding to file info using
{@link #appendFileInfo(byte[], byte[])} name of the block will call readFields to get data
later (DO NOT REUSE)
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileWriterImpl.java