issue-12 sample

This is the sample to reproduce https://github.com/dmak/jaxb-xew-plugin/issues/12.
I use command ```mvn clean generate-sources``` to build project.
If we use ```-Xxew:delete``` option we'll get empty respose class (```ListResponse.java```), but expect to see this field:
```java
@XmlElement(name = "item")
protected List<String> items;
```