How to write a query to find by _id which is not at the top level...

[apara]

We have a structure which embeds a object called survey with it's own _id. For example:

{
    ...
    ...
    survey {
       _id : 4f595cafda06031df450d8ca
       ...
    }

}

The type of survey._id is ObjectId as it is stored in Mongo.

I wrote a finder that looks like this:

    @Query(value="{\"survey._id\" : ?0}")
    Page<SurveySnapshot> findBySurveyId(String surveyId, Pageable page, Sort sort);

Structurally, the class SurveySnapshot contains a member of type Survey called survey which then contains a String of type id:

class SurveySnapshot {
   ...
   private Survey survey
   ...
}

class Survey {
   private String id;
}

But it's not returning anything and the data is there.

Issuing this query to a MongoQuery tool produces results I need:
{"survey._id" : ObjectId("4f595cafda06031df450d8ca")}

However, writing this code:

new BasicQuery("{\"survey._id\" : ObjectId(\"4f595cafda06031df450d8ca\")}")

Throws a com.mongodb.JSONParseException...

Am I doing something wrong in constructing the query in java?

Thanks.
-AP_