@Override
  public byte get(Object o) {
    // Accept int writables and convert them.
    if (o instanceof IntWritable) {
      return (byte) ((IntWritable) o).get();
    }

    return ((ByteWritable) o).get();
  }
The ParquetByteInspector can inspect both ByteWritables and IntWritables into bytes.
ql/src/java/org/apache/hadoop/hive/ql/io/parquet/serde/primitive/ParquetByteInspector.java