@Override
    public void write(DataOutput out) throws IOException {
      out.writeUTF(inputSplit.getClass().getName());
      inputSplit.write(out);
      out.writeUTF(inputFormatClassName);
    }
The position of the first byte in the file to process.
ql/src/java/org/apache/hadoop/hive/ql/io/HiveInputFormat.java