[_, _ <: VR])org.apache.kafka.streams.kstream.KStream[Nothing,VR] exist so that it can be applied to[AnyRef,Double]
required: org.apache.kafka.streams.kstream.ValueMapper[_, _ <: ?found : org.apache.kafka.streams.kstream.ValueM
> inputSchool1KStream();
}Exception in thread: class kafka.streams.join.School cannot be cast to class kafka.streams.join.Person (kafka.streams.join.Schooland