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I've got a spring boot app that defines:

• a REST Controller that writes to a kafka topic, STREAM_TOPIC_IN_QQQ
• a KafkaListener that reads from STREAM_TOPIC_IN_QQQ (groupId="bar") and logs
• a KStream that peeks the topic and logs it, converts it to another type, then writes it to STREAM_TOPIC_OUT_QQQ
• another KafkaListener that reads from STREAM_TOPIC_OUT_QQQ.

(I've been changing the suffix to avoid any possible confusion, and creating the topics by hand, because otherwise I was getting a warning, STREAM_TOPIC_IN_xxx=LEADER_NOT_AVAILABLE and the stream would not run for a minute or so.)

The first listener and the stream seem to be working, but when the listener on the STREAM_OUT_TOPIC tries to deserialize the message, I get the exception below. I am providing the serde in the stream with Produced.with. What do I need to do so that the listener knows the type to deserialize to?

Log

11 Mar 2019 14:34:00,194   DEBUG    [KafkaMessageController [] http-nio-8080-exec-1]   Sending a Kafka Message
11 Mar 2019 14:34:00,236   INFO     [KafkaConfig [] kafka9000-v0.1-b0a60795-0258-48d9-8c87-30fa9a97d7b8-StreamThread-1]   -------------- STREAM_IN_TOPIC peek: Got a greeting in the stream: Hello, World!
11 Mar 2019 14:34:00,241   INFO     [KafkaConfig [] org.springframework.kafka.KafkaListenerEndpointContainer#1-0-C-1]   STREAM_IN_TOPIC Listener: ConsumerRecord: {}ConsumerRecord(topic = STREAM_TOPIC_IN_QQQ, partition = 0, offset = 0, CreateTime = 1552332840188, serialized key size = 1, serialized value size = 34, headers = RecordHeaders(headers = [], isReadOnly = false), key = 1, value = com.teramedica.kafakaex001web.model.Greeting@7b6c8fcc)
11 Mar 2019 14:34:00,243   INFO     [Metadata [] kafka-producer-network-thread | kafka9000-v0.1-b0a60795-0258-48d9-8c87-30fa9a97d7b8-StreamThread-1-producer]   Cluster ID: y48IEZaGQWKcWDVGf4mD6g
11 Mar 2019 14:34:00,367   ERROR    [LoggingErrorHandler [] org.springframework.kafka.KafkaListenerEndpointContainer#0-0-C-1]   Error while processing: ConsumerRecord(topic = STREAM_TOPIC_OUT_QQQ, partition = 0, offset = 0, CreateTime = 1552332840188, serialized key size = 1, serialized value size = 48, headers = RecordHeaders(headers = [RecordHeader(key = springDeserializerExceptionValue, value = [ REDACTED ])], isReadOnly = false), key = 1, value = null)
org.springframework.kafka.support.serializer.DeserializationException: failed to deserialize; nested exception is java.lang.IllegalStateException: No type information in headers and no default type provided
    at org.springframework.kafka.support.serializer.ErrorHandlingDeserializer2.deserializationException(ErrorHandlingDeserializer2.java:204) ~[spring-kafka-2.2.4.RELEASE.jar:2.2.4.RELEASE]

Here's the configuration:

REST (spring mvc):

@RequestMapping("/greeting")
public Greeting greeting(@RequestParam(value = "name", defaultValue = "World") String name) {
    Greeting gr = new Greeting(counter.incrementAndGet(), String.format(msgTemplate, name));
    this.kafkaTemplate.send(K9000Consts.STREAM_TOPIC_IN, "1", gr);
    logger.debug("Sending a Kafka Message");
    return gr;
}

Kafka Config (spring-kafka):

@Bean
public KStream<String, Greeting> kStream(StreamsBuilder kStreamBuilder) {
    KStream<String, Greeting> stream = kStreamBuilder.stream(K9000Consts.STREAM_TOPIC_IN);
    stream.peek((k, greeting) -> {
        logger.info("-------------- STREAM_IN_TOPIC peek: Got a greeting in the stream: {}", greeting.getContent());
    })
          .map((k, v) -> new KeyValue<>(k, new GreetingResponse(v)))
          .to(K9000Consts.STREAM_TOPIC_OUT, Produced.with(stringSerde, new JsonSerde<>(GreetingResponse.class)));
    return stream;
}

@KafkaListener(topics = K9000Consts.STREAM_TOPIC_OUT, groupId="oofda", errorHandler = "myTopicErrorHandler")
public void listenForGreetingResponse(ConsumerRecord<String, GreetingResponse> cr) throws Exception {
    logger.info("STREAM_OUT_TOPIC Listener : {}" + cr.toString());
}

@KafkaListener(topics = K9000Consts.STREAM_TOPIC_IN, groupId = "bar")
public void listenForGreetingResponses(ConsumerRecord<String, Greeting> cr) throws Exception {
    logger.info("STREAM_IN_TOPIC Listener: ConsumerRecord: {}" + cr.toString());
}

application.yml

spring:
kafka:
  bootstrap-servers:  localhost:9092
  consumer:
    group-id: foo
    auto-offset-reset: latest
    key-deserializer: org.springframework.kafka.support.serializer.ErrorHandlingDeserializer2
    value-deserializer: org.springframework.kafka.support.serializer.ErrorHandlingDeserializer2
    properties:
      spring.json.trusted.packages: com.teramedica.kafakaex001web.model
      spring.deserializer.key.delegate.class: org.apache.kafka.common.serialization.StringDeserializer
      spring.deserializer.value.delegate.class: org.springframework.kafka.support.serializer.JsonDeserializer
  producer:
    key-serializer: org.apache.kafka.common.serialization.StringSerializer
    value-serializer: org.springframework.kafka.support.serializer.JsonSerializer
  streams:
    application-id: kafka9000-v0.1
    properties: # properties not explicitly handled by KafkaProperties.streams
      default.key.serde: org.apache.kafka.common.serialization.Serdes$StringSerde
      default.value.serde: org.springframework.kafka.support.serializer.JsonSerde
      spring.json.trusted.packages: com.teramedica.kafakaex001web.model

Answers

See the documentation.

Specifically...

JsonDeserializer.VALUE_DEFAULT_TYPE: Fallback type for deserialization of values if no header information is present.

It's spring.json.value.default.type

You can also set spring.json.use.type.headers (default true) to prevent even looking for headers.

The deserializer automatically trusts the package of the default type so it's not necessary to add it there.

EDIT

However, also see Spring Messaging Message Conversion.

Use a BytesDeserializer and BytesJsonMessageConverter and the framework will pass the method parameter type as the target for conversion.