keyBy后滚动聚合（Rolling Aggregation）报错：org.apache.flink.api.common.InvalidProgramException: Specifying keys via field positions is only valid for tuple data types. Type: GenericType
报错图如下
Exception in thread "main" org.apache.flink.api.common.InvalidProgramException: Specifying keys via field positions is only valid for tuple data types. Type: GenericType<scala.Tup