I'm trying to leverage json4s for parsing the StructType from Spark.
```
scala> import org.apache.spark.sql.types._
scala> case class Person(name: StructType)
defined class Person
scala> import org.json4s._
import org.json4s._
scala> import org.json4s.jackson.JsonMethods._
import org.json4s.j
I??m implementing the materialized feature for Spark. I have built a customized
listener that logs the logical plan and physical plan of each sql query. After
some analysis, I can get the most valuable subtree that needs to be
materialized. Then I need to restore the subtree of the plan back to
