我正在为一个kafkaproducer单元测试一个非常简单的 Package 类，其send方法如下

public class EntityProducer { 
    private final KafkaProducer<byte[], byte[]> kafkaProducer;
    private final String topic;

    EntityProducer(KafkaProducer<byte[], byte[]> kafkaProducer, String topic)
    {
        this.kafkaProducer = kafkaProducer;
        this.topic = topic;
    }

    public void send(String id, BusinessEntity entity) throws Exception
    {
        ProducerRecord<byte[], byte[]> record = new ProducerRecord<>(
            this.topic,
            Transformer.HexStringToByteArray(id),
            entity.serialize()
        );
        kafkaProducer.send(record);
        kafkaProducer.flush();
    }
}

单元测试如下：

@Test public void send() throws Exception
{
    @SuppressWarnings("unchecked")
    KafkaProducer<byte[], byte[]> mockKafkaProducer = Mockito.mock(KafkaProducer.class);
    String topic = "mock topic";
    EntityProducer producer = new EntityProducer(mockKafkaProducer, topic);

    BusinessEntitiy mockedEntity = Mockito.mock(BusinessEntity.class);
    byte[] serialized = new byte[]{1,2,3};
    when(mockedCipMsg.serialize()).thenReturn(serialized);

    String id = "B441B675-294E-4C25-A4B1-122CD3A60DD2";
    producer.send(id, mockedEntity);

    verify(mockKafkaProducer).send(
        new ProducerRecord<>(
            topic,
            Transformer.HexStringToByteArray(id),
            mockedEntity.serialize()
        )
    );

    verify(mockKafkaProducer).flush();

第一个验证方法失败，因此测试失败，并显示以下消息：

Argument(s) are different! Wanted:
kafkaProducer.send(
    ProducerRecord(topic=mock topic, partition=null, key=[B@181e731e, value=[B@35645047, timestamp=null)
);
-> at xxx.EntityProducerTest.send(EntityProducerTest.java:33)
Actual invocation has different arguments:
kafkaProducer.send(
    ProducerRecord(topic=mock topic, partition=null, key=[B@6f44a157, value=[B@35645047, timestamp=null)
);

最相关的是producerrecord的键不相同，值看起来相同
单元测试的方向是否正确？我怎样才能通过考试？
谨致问候。