解组时jaxb为null值

Question

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE xml>
<Settings version="3" xmlns="urn:Adapter-v3">
  <Connections>      
    <Connection name ="A" description="DEV">
      <SaveVersion version="M" siteURL="https://example.com" />
      <Save>
        <Id>id123</Id>
        <Client>hello</Client>
      </Save>   
    </Connection>    
    <Connection name ="B" description="DEV1">
      <SaveVersion version="M" siteURL="https://example.com" />    
      <Auth>
        <UserId>id123</UserId>
        <Password>pass</Password>
      </Auth>
    </Connection>
    </Connections>
  <Mappings>
    <Mapping cont="AA" auction="A1">
      <Description>Desc</Description>
      <Content    
        attr1="IO"
        attr2="d"
        attr3="Information"
        attr4="false"

        <Element enabled="false" count="200" prefix="DocLib_" itemPrefix="0" />
        <Sub enabled="false" count="100" prefix="Folder_" itemPrefix="0" />
        <FilenameA auction="N" delay="3" />
      </Content>
     </Mapping>
  <Mapping cont="AB" auction="SharePointOLDev1">
      <Description>Desc</Description>
      <Content    
        attr1="IO"
        attr2="d"
        attr3="Information"
        attr4="false"

        <Element enabled="false" count="200" prefix="DocLib_" itemPrefix="0" />
        <Sub enabled="false" count="100" prefix="1" itemPrefix="0" />     
      </Content>
     </Mapping>
  </Mappings>
  <TypeMappings>
    <TypeMapping Type="rfid" ext="msg" />
  </TypeMappings>

</Settings>

尝试将上述xml文件解组为java对象。 使用xjc工具生成Settings.java和ObjectFactory.java文件。这些文件部署在src文件夹中（以及其他java文件。） 当我解组时，我得到Connections，Mappings和TypeMappings的空值。 有没有我缺少的步骤？

public class JAXBImpl{
public static void main(String args[]){
        JAXBContext jaxbContext;
        Settings que= null;
        jaxbContext = JAXBContext.newInstance(Settings.class);
         Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
         que= (Settings) jaxbUnmarshaller.unmarshal(file);

         System.out.println(que.getConnections().getConnection());
}
}