private static Tuple transformToTuple(List<?> objList, HCatSchema hs) throws Exception {
    if (objList == null) {
      return null;
    }
    Tuple t = tupFac.newTuple(objList.size());
    List<HCatFieldSchema> subFields = hs.getFields();
    for (int i = 0; i < subFields.size(); i++) {
      t.set(i, extractPigObject(objList.get(i), subFields.get(i)));
    }
    return t;
  }
Converts object from Hive's value system to Pig's value system
see HCatBaseStorer#getJavaObj() for Pig->Hive conversion 
@param o object from Hive value system
@return object in Pig value system
hcatalog/hcatalog-pig-adapter/src/main/java/org/apache/hive/hcatalog/pig/PigHCatUtil.java