@Override
  public void prepareForWrite(final RecordConsumer recordConsumer) {
    writer = new DataWritableWriter(recordConsumer, schema, defaultDateProleptic, conf);
  }
DataWritableWriteSupport is a WriteSupport for the DataWritableWriter
ql/src/java/org/apache/hadoop/hive/ql/io/parquet/write/DataWritableWriteSupport.java