why is my jackson implementation failing to properly format a list in xml?

Question

My jackson implementation that should return a List<Alert>returns this instead:

<List xmlns="">
    <script id="tinyhippos-injected"/>
    <item>
        <id>8a1f88cb-e9ee-4164-a0ca-72f57c349b7e</id>
        (...)
    </item>
</List>

Though I understand the xmlns="" is harmless, I'm not so sure about the <script /> bit.

Also, since my desired output is a list of Alert, how come I'm getting a list of item?

My Alert class has been annotated as:

@Entity
@Table(name="alert")
@JacksonXmlRootElement(localName = "alert") 
@JsonIdentityInfo(generator=ObjectIdGenerators.PropertyGenerator.class, property="id")
public class Alert extends BasePojo {

    private static final long serialVersionUID = 1L;

    @JacksonXmlProperty(localName = "code")
    @Column(name = "code", nullable = false, unique = true)
    private String code;

    (...)
    // getters and setters
}

The method that returns the list is:

@GET
@RequestMapping(value = "/list/{companyId}/{agentName}/{pollInterval}/{lastExecutionDate}", produces = XML_CONTENT_TYPE)
public List<Alert> listAlertsByAgentId(@PathVariable String companyId, 
                                              @PathVariable String agentName, 
                                              @PathVariable String pollInterval, 
                                              @PathVariable String lastExecutionDate) 
                                              throws IOException {

    List<Alert> list = new ArrayList<Alert>();

    Agent agent = alertService.findAgentByAgentName(agentName);
    agent.setPollInterval(Integer.parseInt(pollInterval));

    int year = Integer.parseInt(lastExecutionDate.substring(0, 4));
    int month = Integer.parseInt(lastExecutionDate.substring(4, 6)) - 1;
    int date = Integer.parseInt(lastExecutionDate.substring(6, 8));
    int hour = Integer.parseInt(lastExecutionDate.substring(8, 10));
    int minute = Integer.parseInt(lastExecutionDate.substring(10, 12));
    int second = Integer.parseInt(lastExecutionDate.substring(12, 14));

    Calendar cal = Calendar.getInstance();
    cal.set(year, month, date, hour, minute, second);

    agent.setLastExecutionDate(cal.getTime());

    alertService.updateAgent(agent);
    list = fetchAlertListByAgentName(companyId, agentName);

    if(list == null || list.size() == 0 || list.isEmpty()) {
        list = new ArrayList<Alert>();
    }
    return list;
}

What am I not seeing here?