private static VectorExpressionWriter genVectorExpressionWritable(
      SettableStructObjectInspector objInspector,
      StructField fieldRef,
      VectorExpressionWriter baseWriter) throws HiveException {
    return new VectorExpressionWriterSetter().init(objInspector, fieldRef, baseWriter);
  }
VectorExpressionWriterSetter helper for vector expression writers that use
settable ObjectInspector fields to assign the values.
This is used by the OrcStruct serialization (eg. CREATE TABLE ... AS ...)
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/VectorExpressionWriterFactory.java