Avro ReflectDatumWriter中的NullPointerException

我对Java对象的Avro序列化有一个特定的问题.我有从xsd架构生成的POJO,然后我尝试使用av​​ro序列化放置在kafka主题上.一些xmlElements是可选的

测试消息如下所示:

@XmlRootElement(name = "message")
public class Testmessage {

  @XmlElement
  public String id;


  @XmlElement
  public String name;

  public Testmessage(String id, String name) {
    this.id = id;
    this.name = name;
  }

  public Testmessage() { }

  @Override
  public String toString() {
    return "Message{" +
        "id='" + id + '\'' +
        ", name=" + name +
        '}';
  }
}

序列化和放置主题的方法是:

public void sendMessage(Testmessage msg) throws Exception{

    DatumWriter writer = new ReflectDatumWriter(Testmessage.class); 
    ByteArrayOutputStream os = new ByteArrayOutputStream();

    Encoder encoder = EncoderFactory.get().binaryEncoder(os, null);
    writer.write(msg, encoder);
    encoder.flush();
    os.close();
    KeyedMessage data = new KeyedMessage(TOPIC_NAME, os.toByteArray());

    producer.send(data);

}

当我发送两个字段时,所有按预期工作.如果我将其中一个字段置空或将其遗漏,我会从写入中获取NPE.

java.lang.NullPointerException: in Testmessage in string null of string in field id of    Testmessage
at org.apache.avro.reflect.ReflectDatumWriter.write(ReflectDatumWriter.java:145)
at org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:58)

有任何想法吗？或指出我正确的方向

谢谢!