@Override
  public HFileContext getFileContext() {
    return hFileContext;
  }
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