notification-portlet-api/src/main/java/org/jasig/portlet/notice/NotificationResponse.java
public NotificationResponse combine(NotificationResponse response) {
        NotificationResponse rslt = new NotificationResponse(this);
        rslt.addCategories(response.getCategories());
        rslt.addErrors(response.getErrors());
        return rslt;
    }
public NotificationResponse combine(NotificationResponse response) {
        NotificationResponse rslt = new NotificationResponse(this);
        rslt.addCategories(response.getCategories());
        rslt.addErrors(response.getErrors());
        return rslt;
    }
Combine the contents of this response with the provided response and
return a <b>new instance</b> of {@link NotificationResponse}.  The
original instances are unchanged.

@param response A new {@link NotificationResponse} that contains data from both originals