What is spring.kafka.streams and how do you use Kafka Streams in Spring Boot?

Spring Kafka auto-configures Kafka Streams when StreamsConfig properties are provided: spring.kafka.streams.application-id=my-streams-app, spring.kafka.streams.bootstrap-servers, spring.kafka.streams.default-key-serde, spring.kafka.streams.default-value-serde. Create a @Bean KStream<K,V> and use the StreamsBuilderFactoryBean. Spring manages the KafkaStreams lifecycle (start, stop, health check). For health: implement StreamsBuilderFactoryBeanCustomizer. Use StreamsBuilder DSL for stream processing. Spring Boot's actuator health indicator shows Streams state.

Expected key concepts: spring.kafka.streams, application-id, StreamsBuilderFactoryBean, KStream, StreamsBuilder, lifecycle, health check, StreamsBuilderFactoryBeanCustomizer, actuator, default-key-serde