application.yml

server:
  port: 9001


spring:
  cloud:
    stream:
      function:
        definition: fizzBuzzProducer;fizzBuzzProcessor;fizzBuzzConsumer

      bindings:
        fizzBuzzProducer-out-0:
          destination: numbers
        fizzBuzzProcessor-in-0:
          destination: numbers
        fizzBuzzProcessor-out-0:
          destination: fizz-buzz
        fizzBuzzConsumer-in-0:
          destination: fizz-buzz
      kafka:
        binder:
          brokers: localhost:9092
          auto-create-topics: true

Hi @ereshzealous
I think it should be spring.cloud.function.definition instead of spring.cloud.stream.function.definition

In the text of your article, it's correct: https://medium.com/geekculture/spring-cloud-streams-with-functional-programming-model-93d49696584c, but not in this application.yml which is shown below the text