With a repeatable XML element you may want to distinguish between a list that is absent and an empty list. For this, you need some additional element bracketing, or "wrapping", for the repeated element, as indicated in the XML snippet below.

<parent>
  <wrapper>
    <item>A</item>
    <item>B</item>
    <item>C</item>
  </wrapper>
</parent>

@XmlType( name="ParentType" )
public class ParentType {
    protected List item;
    public ParentType(){ ... }
    @XmlElement( name="item" )
    @XmlElementWrapper( name="wrapper" )
    public List getItem(){
        if( item == null ) item = new ArrayList();
        return item;
    }
}