使用以下代码，我发送Elasticsearch文档以进行索引。我尝试将基本对象转换为JSON并通过生产者发送。但是，每条消息（从控制台检查）都附加了乱码，例如
- t。{“ productId”：2455

public boolean sendMessage()
{
    PageRequest page = new PageRequest(0, 1); 
    Product p = product.findByName("Cream", page).getContent().get(0);
    String json = "";
    ObjectMapper mapper = new ObjectMapper();
    try {
        json = mapper.writeValueAsString(p);
    } catch (JsonProcessingException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }       
    logger.info("JSON = " + json);

    boolean status =  inputToKafka.send(org.springframework.integration.support.MessageBuilder.withPayload(json).build());
    try {
        Thread.sleep(10000);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    return status;
}

出站配置

 <?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:int="http://www.springframework.org/schema/integration"
       xmlns:int-kafka="http://www.springframework.org/schema/integration/kafka"
       xmlns:task="http://www.springframework.org/schema/task"
       xsi:schemaLocation="http://www.springframework.org/schema/integration/kafka http://www.springframework.org/schema/integration/kafka/spring-integration-kafka.xsd
        http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task.xsd">

    <int:channel id="inputToKafka">
        <int:queue/>
    </int:channel>

    <int-kafka:outbound-channel-adapter
            id="kafkaOutboundChannelAdapter"
            kafka-producer-context-ref="kafkaProducerContext"
            channel="inputToKafka">
        <int:poller fixed-delay="1000" time-unit="MILLISECONDS" receive-timeout="0" task-executor="taskExecutor"/>
    </int-kafka:outbound-channel-adapter>

    <task:executor id="taskExecutor" pool-size="5" keep-alive="120" queue-capacity="500"/>

    <int-kafka:producer-context id="kafkaProducerContext">
        <int-kafka:producer-configurations>
            <int-kafka:producer-configuration broker-list="localhost:9092"
                                              topic="test_topic"
                                              compression-codec="default"/>
        </int-kafka:producer-configurations>
    </int-kafka:producer-context>

    </beans>

有什么线索吗？

使用的插件：Spring Extension Kafka