问org.apache.flink.table.api.TableException:结果的重要性[3]与请求类型的number[2]不匹配

EN

import org.apache.flink.api.scala.ExecutionEnvironment
import org.apache.flink.table.api.TableEnvironment

import org.apache.flink.api.scala._
case class Person(name: String, age: Int)
object TableTest {
  def main(args: Array[String]): Unit = {
    val env = ExecutionEnvironment.getExecutionEnvironment
    val te = TableEnvironment.getTableEnvironment(env)
    val ds = env.fromCollection(Seq(Person("a",20), Person("b",40), Person("c", 60)))
    te.registerDataSet("person", ds)

    te.toDataSet[Person](table).print()


    val table = te.sqlQuery(
      """
         select name,age,
             case
                when age <= 20 then 'A'
                when age <=40 then 'B'
                when age <= 60 then 'C'
                else 'D'
            end as age_level
            from person
      """.stripMargin(' '))
    te.toDataSet[Person](table).print()
  }
}

Exception in thread "main" org.apache.flink.table.api.TableException: Arity [3] of result [ArrayBuffer(String, Integer, String)] does not match the number[2] of requested type [com.flink.table.Person(name: String, age: Integer)].
    at org.apache.flink.table.api.TableEnvironment.generateRowConverterFunction(TableEnvironment.scala:1165)
    at org.apache.flink.table.api.BatchTableEnvironment.getConversionMapper(BatchTableEnvironment.scala:339)
    at org.apache.flink.table.api.BatchTableEnvironment.translate(BatchTableEnvironment.scala:504)
    at org.apache.flink.table.api.BatchTableEnvironment.translate(BatchTableEnvironment.scala:476)
    at org.apache.flink.table.api.scala.BatchTableEnvironment.toDataSet(BatchTableEnvironment.scala:141)
    at com.flink.table.TableTest$.main(TableTest.scala:37)
    at com.flink.table.TableTest.main(TableTest.scala)