@Override
  public Writable doSerialize(Object obj, ObjectInspector objInspector)
    throws SerDeException {
    return jsonSerde.serialize(obj, objInspector);
  }
Given an object and object inspector pair, traverse the object
and generate a Text representation of the object.
hcatalog/core/src/main/java/org/apache/hive/hcatalog/data/JsonSerDe.java