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Here are some tips, including the required configurations and code samples, to help you implement a Kafka consumer in Java.

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Required dependencies

Ensure that you have the following dependencies in your project: 
<dependency>
    <groupId>org.springframework.kafka</groupId>
    <artifactId>spring-kafka</artifactId>
</dependency>

<dependency>
    <groupId>io.strimzi</groupId>
    <artifactId>kafka-oauth-client</artifactId>
    <version>0.6.1</version>
</dependency>

<dependency>
    <groupId>org.apache.kafka</groupId>
    <artifactId>kafka-clients</artifactId>
    <version>2.5.1</version>
</dependency>

<dependency>
    <groupId>io.opentracing.contrib</groupId>
    <artifactId>opentracing-kafka-client</artifactId>
    <version>0.1.13</version>
</dependency>

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Configuration

Ensure that you have the following configuration in your application.yml or application.properties file: 
spring:
  kafka:
    bootstrap-servers: localhost:9092
    security.protocol: "PLAINTEXT"
    consumer:
      key-serializer: org.apache.kafka.common.serialization.StringSerializer
      value-serializer: org.springframework.kafka.support.serializer.JsonSerializer
      properties:
        max:
          partition:
            fetch:
              bytes: ${KAFKA_MESSAGE_MAX_BYTES:52428800} #50MB

kafka:
  consumer:
    group-id: 
    ...
    threads:
    ...

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Code sample for a Kafka Listener

Here’s an example of a Kafka listener method: 
@KafkaListener(topics = "TOPIC_NAME_HERE")
public void listen(ConsumerRecord<String, String> record) throws JsonProcessingException {

  SomeDTO request = objectMapper.readValue(record.value(), SomeDTO.class);

  // process received DTO
  // Make sure to replace *"TOPIC_NAME_HERE"* with the actual name of the Kafka topic you want to consume from. Additionally, ensure that you have the necessary serialization and deserialization logic based on your specific use case.
}
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