@Override
    public Entry<String, NotificationConfiguration> unmarshall(StaxUnmarshallerContext context) throws Exception {
        int originalDepth = context.getCurrentDepth();
        int targetDepth = originalDepth + 1;

        if (context.isStartOfDocument()) {
            targetDepth += 1;
        }

        T topicConfig = createConfiguration();
        String id = null;

        while (true) {
            XMLEvent xmlEvent = context.nextEvent();
            if (xmlEvent.isEndDocument()) {
                return new SimpleEntry<String, NotificationConfiguration>(id, topicConfig);
            }

            if (xmlEvent.isAttribute() || xmlEvent.isStartElement()) {
                if (handleXmlEvent(topicConfig, context, targetDepth)) {
                    // Do nothing, subclass has handled it
                } else if (context.testExpression("Id", targetDepth)) {
                    id = StringStaxUnmarshaller.getInstance().unmarshall(context);
                } else if (context.testExpression("Event", targetDepth)) {
                    topicConfig.addEvent(StringStaxUnmarshaller.getInstance().unmarshall(context));
                } else if (context.testExpression("Filter", targetDepth)) {
                    topicConfig.setFilter(FilterStaxUnmarshaller.getInstance().unmarshall(context));
                }
            } else if (xmlEvent.isEndElement()) {
                if (context.getCurrentDepth() < originalDepth) {
                    return new SimpleEntry<String, NotificationConfiguration>(id, topicConfig);
                }
            }
        }
    }
Id (aka configuration name) isn't modeled on the actual {@link NotificationConfiguration}
class but as the key name in the map of configurations in
{@link BucketNotificationConfiguration}
aws-java-sdk-s3/src/main/java/com/amazonaws/services/s3/model/transform/NotificationConfigurationStaxUnmarshaller.java