ReceiverConfig.java

@Configuration
@EnableKafka
public class ReceiverConfig {

    @Value("${spring.kafka.bootstrap-servers}")
    private String bootstrapServers;

    @Value("${spring.kafka.consumer.group-id}")
    private String groupId;

    @Value("${spring.kafka.consumer.auto-offset-reset}")
    private String autoOffsetReset;

    @Bean
    public Map<String, Object> consumerConfigs() {

        Map<String, Object> props = new HashMap<>();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        props.put(ConsumerConfig.GROUP_ID_CONFIG, groupId);
        props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, autoOffsetReset);

        return props;
    }

    @Bean
    public ConsumerFactory<String, String> consumerFactory() {

        return new DefaultKafkaConsumerFactory<>(consumerConfigs(), new StringDeserializer(),
                new StringDeserializer());
    }

    @Bean
    ConcurrentKafkaListenerContainerFactory<String, String> kafkaListenerContainerFactory() {

        ConcurrentKafkaListenerContainerFactory<String, String> factory =
                new ConcurrentKafkaListenerContainerFactory<>();
        factory.setConsumerFactory(consumerFactory());
        factory.setMessageConverter(new StringJsonMessageConverter());

        return factory;
    }

    @Bean
    public Receiver receiver() {

        return new Receiver();
    }
}