MongoDB Abstract Type Mapping excludes _class when Pushing

[pugmire]

I am have the following class hierarchy.

public class Sensor {
  List<Event> events;
}

public abstract class Event { ... }

public class PressureEvent extends Event { ... }

When I save a Sensor instance with an event, the _class property is added.

mongoTemplate.save(sensor, Sensor.class);

{ "_class" : "com.acme.Sensor",
   "events" : [
		{
			 "_class" : "com.acme.PressureEvent",
                         ...
		}
   ]
}

When I push an event onto the Sensor instance's event array the _class property is not added.

mongoTemplate.updateFirst(new Query(Criteria.where("_id").is(new ObjectId(sensor.getId()))), new Update().push("events", event), Sensor.class);

{ "_class" : "com.acme.Sensor",
   "events" : [
		{
			 ...
		}
   ]
}

After an Event instance without a _class field is pushed onto the events array the sensor instance cannot be loaded due to the mapper not knowing the type of class.

org.springframework.data.mapping.model.MappingInstantiationException: Could not instantiate bean class [com.acme.Event]: Is it an abstract class?; nested exception is java.lang.InstantiationException

Is this a bug or the intended behavior? Am I pushing onto the array improperly?

I am using spring-data-mongodb-1.0.1.RELEASE.

[zackangelo]

Did you find a resolution to this? I'm running into the same issue on 1.0.2 RELEASE.