Spring Boot Auto Configuration Failed Loading Spring Kafka Properties - spring-boot

Question

Spring boot failed to load properties. Here are the properties that i am using through the yaml file.
spring:
kafka:
bootstrap-servers: localhost:9092
consumer:
auto-commit-interval: 100
enable-auto-commit: true
group-id: ********************
auto-offset-reset: earliest
value-deserializer: org.springframework.kafka.support.serializer.JsonDeserializer
producer:
batch-size: 16384
buffer-memory: 33554432
retries: 0
value-serializer: org.springframework.kafka.support.serializer.JsonSerializer
listener:
poll-timeout: 20000
The exception i am getting is this
Caused by: java.lang.IllegalAccessException: Class org.apache.kafka.common.utils.Utils can not access a member of class org.springframework.kafka.support.serializer.JsonDeserializer with modifiers "protected"
I think the constructor is protected. Please provide a way to instantiate this.

Answer 1

That's correct. See:
protected JsonDeserializer() {
this((Class<T>) null);
}
protected JsonDeserializer(ObjectMapper objectMapper) {
this(null, objectMapper);
}
public JsonDeserializer(Class<T> targetType) {
this(targetType, new ObjectMapper());
this.objectMapper.configure(MapperFeature.DEFAULT_VIEW_INCLUSION, false);
this.objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
}
The JsonDeserializer isn't designed to be instantiated by the default constructor because it needs to know the targetType to deserialize.
You can extend this class to your particular type:
public class FooJsonDeserializer extends JsonDeserializer<Foo> { }
and use already this as class value for that value-deserializer property.
Or you can consider to customize the DefaultKafkaConsumerFactory:
#Bean
public ConsumerFactory<?, ?> kafkaConsumerFactory(KafkaProperties properties) {
Map<String, Object> consumerProperties = properties.buildConsumerProperties();
consumerProperties.put(CommonClientConfigs.METRIC_REPORTER_CLASSES_CONFIG,
MyConsumerMetricsReporter.class);
DefaultKafkaConsumerFactory<Object, Object> consumerFactory =
new DefaultKafkaConsumerFactory<>(consumerProperties);
consumerFactory.setValueDeserializer(new JsonDeserializer<>(Foo.class));
return consumerFactory;
}