@Override
  public Object setStructFieldData(Object struct, StructField field, Object fieldValue) {
    final ArrayList<Object> list = (ArrayList<Object>) struct;
    list.set(((StructFieldImpl) field).getIndex(), fieldValue);
    return list;
  }
The ArrayWritableObjectInspector will inspect an ArrayWritable, considering it as a Hive struct.<br>
It can also inspect a List if Hive decides to inspect the result of an inspection.
ql/src/java/org/apache/hadoop/hive/ql/io/parquet/serde/ArrayWritableObjectInspector.java