Xstream不反序列化自定义对象列表

Question

使用xStream

反序列化隐式集合时遇到一些麻烦

我有两个班级：

一：

@XStreamAlias("instances")
public class ServerInstances {

  public ServerInstances(){
      instances = new ArrayList<>();
  }

  @XStreamImplicit(itemFieldName = "instance")
  private List<ServerInstance> instances;

  ...add, get, size, etc.
}

二：

@XStreamAlias("instance")
public class ServerInstance {

  @XStreamAlias("version")
  private String version;

  @XStreamAlias("environment")
  private String environment;

  @XStreamAlias("user")    
  private String user;

  @XStreamAlias("timestamp")
  private DateTime timeStamp;

  getter, setter, etc.

}

当我序列化ServerInstances类

时

    xStream = new XStream2();
    xStream.registerConverter(new DateTimeConverter());
    xStream.processAnnotations(new Class[] {ServerInstances.class, ServerInstance.class});
    xStream.toXMLUTF8(object, outputStream);

我得到了很好的xml：

<?xml version="1.0" encoding="UTF-8"?>
<instances plugin="jenkins-deployment-dashboard@0.0.1">
  <instance>
    <version>1</version>
    <environment>i1</environment>
    <user>u1</user>
    <timestamp>2014-10-10T11:42:30.957+02:00</timestamp>
  </instance>
  <instance>
    <version>2</version>
    <environment>i2</environment>
    <user>u2</user>
    <timestamp>2014-10-10T11:42:30.991+02:00</timestamp>
  </instance>
</instances>

但是当我尝试反序列化时

xStream = new XStream2();
xStream.registerConverter(new DateTimeConverter());
xStream.processAnnotations(new Class[] {ServerInstances.class, ServerInstance.class});
ServerInstances instances = (ServerInstances)xStream.fromXml(inputStream);

我得到一个ServerInstances的实例，其中List为null。 我还试图通过使用xStream.alias（...）和xStream.addImplicitCollection（...）来声明别名，这会产生相同的结果。我不知道该怎么做了。