<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns4:GetKeyResponse xmlns:ns2="abc" xmlns:ns4="defg" xmlns:ns3="hik">
    <key>
        <item>
            <key>1234</key>
            <keyType>UNLOCK_CODE</keyType>
        </item>
        <item>
            <key>www.test.com</key>
            <keyType>DOWNLOAD_URL</keyType>
        </item>
    </key>
    <returnCode>200</returnCode>
    <returnMessage>OK</returnMessage>
</ns4:GetKeyResponse>

com.sun.xml.internal.bind.v2.runtime.IllegalAnnotationsException: 3 counts of IllegalAnnotationExceptions
Class has two properties of the same name "key"

public class DigitalRightsResponse {


    @XmlElement(name="key")
    DigitalRightsKey key;
    @XmlElement(name="returnCode")
    String returnCode;
    @XmlElement(name="returnMessage")
    String returnMessage;

    public DigitalRightsKey getKey() {
        return key;
    }
    public void setKey(DigitalRightsKey key) {
        this.key = key;
    }
    public String getReturnCode() {
        return returnCode;
    }
    public void setReturnCode(String returnCode) {
        this.returnCode = returnCode;
    }
    public String getReturnMessage() {
        return returnMessage;
    }
    public void setReturnMessage(String returnMessage) {
        this.returnMessage = returnMessage;
    }

}

public class DigitalRightsKey {

    DigitalRightsResponseItem[] items;

    public DigitalRightsResponseItem[] getItems() {
        return items;
    }

    public void setItems(DigitalRightsResponseItem[] items) {
        this.items = items;
    }

}

@XmlRootElement(name = "item")
public class DigitalRightsResponseItem {

    private String keyType;

    private String key;

    public String getKeyType ()
    {
        return keyType;
    }

    public void setKeyType (String keyType)
    {
        this.keyType = keyType;
    }

    public String getKey ()
    {
        return key;
    }

    public void setKey (String key)
    {
        this.key = key;
    }

    @Override
    public String toString()
    {
        return "ClassPojo [keyType = "+keyType+", key = "+key+"]";
    }
}

public static DigitalRightsResponse DRResponseXMLToObject(String xml) throws JAXBException{
        JAXBContext jaxbContext = JAXBContext.newInstance(DigitalRightsResponse.class);
        Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();

        StringReader reader = new StringReader(xml);
        DigitalRightsResponse response = (DigitalRightsResponse) unmarshaller.unmarshal(reader);
        return response;
    }