As part of learning kafka streams I am trying to write a streaming application that sums up the amount in bank transactions. The bank transactions are read from a topic as json objects. I get a compilation error for the below code

I have a scenario where there is a Kafka producer streaming app producing json payload to a topic.
I want to create a stream application where it should do a count for every message that arrive into that topic during every one hour. And towards the end of every one hour it should call a method that should create a sample payload that says the count . Count may vary based on time window. I took help from chatgpt and copilot.
Nothing seems to be working. Need a sample Java application for the same.