How can I set default-key/value-serde in application.properties - Spring Boot Kafka Streams

Question

I'm making a Spring Boot Kafka Streams application (Not Spring Cloud)

When set up configuration, as I know, there are two way to set configuration.

The first way is making a config bean like below

@Configuration
@EnableKafka
@EnableKafkaStreams
public class KafkaConfig {
 
    @Value(value = "${spring.kafka.bootstrap-servers}")
    private String bootstrapAddress;
 
    @Bean(name = KafkaStreamsDefaultConfiguration.DEFAULT_STREAMS_CONFIG_BEAN_NAME)
    KafkaStreamsConfiguration kStreamsConfig() {
        Map<String, Object> props = new HashMap<>();
        props.put(APPLICATION_ID_CONFIG, "streams-app");
        props.put(BOOTSTRAP_SERVERS_CONFIG, bootstrapAddress);
        props.put(DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
        props.put(DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());

        return new KafkaStreamsConfiguration(props);
    }
}

Second way is set config at application.properties

spring.kafka.streams.application-id=streams-app
spring.kafka.streams.bootstrap-servers=localhost:9092

In the first way, StreamsConfig has DEFAULT_KEY/VALUE_SERDE_CLASS_CONFIG properties to set default.key.serde and default.value.serde.

But in application.properties, I don't know how can set that properties. also autocompletion doesn't exist.

In short, Is there a way to set default.key.serde and default.value.serde in application.properties?

I tried

spring.kafka.streams.default-key-serde
spring.kafka.streams.default.key.serde
spring.kafka.streams.default-key-serde-class
spring.kafka.streams.properties.default-key-serde

etc. But nothing works

Answer 1

Use square brackets

spring.kafka.streams.properties[default.key.serde]="..."

https://docs.spring.io/spring-boot/docs/current/reference/html/messaging.html#messaging.kafka.additional-properties