public ExprNodeDesc[] getPartitionExprNodeDescs() {
    return partitionExprNodeDescs;
  }
VectorPTFDesc.

Extra parameters beyond PTFDesc just for the VectorPTFOperator.

We don't extend PTFDesc because the base OperatorDesc doesn't support
clone and adding it is a lot work for little gain.
ql/src/java/org/apache/hadoop/hive/ql/plan/VectorPTFDesc.java