code: public void write(DataOutput out) throws IOException {
      out.writeInt(deleteList.size());
      for (Term term : deleteList) {
        Text.writeString(out, term.field());
        Text.writeString(out, term.text());
      }
  
      String[] files = dir.list();
      RAMDirectoryUtil.writeRAMFiles(out, dir, files);
    }
docs: /* (non-Javadoc)
  @see org.apache.hadoop.io.Writable#write(java.io.DataOutput)