public StructObjectInspector initialize(StructObjectInspector argOIs)
      throws UDFArgumentException {
    List<? extends StructField> inputFields = argOIs.getAllStructFieldRefs();
    ObjectInspector[] udtfInputOIs = new ObjectInspector[inputFields.size()];
    for (int i = 0; i < inputFields.size(); i++) {
      udtfInputOIs[i] = inputFields.get(i).getFieldObjectInspector();
    }
    return initialize(udtfInputOIs);
  }
Additionally setup GenericUDTF with MapredContext before initializing.
This is only called in runtime of MapRedTask.

@param mapredContext context
ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDTF.java