public ExprNodeDesc getKeyCol() {
      ExprNodeDesc keyCol = desc.getTarget();
      if (keyCol != null) {
        return keyCol;
      }

      return generator.getConf().getKeyCols().get(desc.getKeyIndex());
    }
Find out if this predicate constains the synthetic predicate to be removed
ql/src/java/org/apache/hadoop/hive/ql/parse/GenTezUtils.java