gistfile1.java

// entity is pretty much a pojo
@Entity(value = "activityStream", noClassnameStored = true)
public class ActivityStream extends BaseEntity {
    private String userId;
    private String todoId;
    private String todoListId;
    private String suggestionId;
    private String actorId;
    private ActivityType activityType; // turned into an int before inserting

    ...getters...
    ...setters...
}

// basic insert using Morphia
public class ActivityStreamDao extends BaseDao<ActivityStream, ObjectId> {
    @Override
    public Key<ActivityStream> save(ActivityStream entity) {
        return super.save(entity, WriteConcern.NONE);
    }
}