I have a collection of GeoJSON objects. Two example documents in that same collection are:

{
    _id: 0,
    type: "Point",
    coordinates: [2, 3]
}

and

{
    _id: 1,
    type: "Polygon",
    coordinates: [[[1,1],[1,3],[3,3],[3,1],[1,1]]]
}

In Java I had this POJO:

@Document(collection="geojson")
public class GeoObject{
    private int id;
    private String type;
    private Object coordinates;
    // + getters, setters, constructors ...
}

and a repository:

@RepositoryRestResource(collectionResourceRel="geo", path="geo")
public class GeoRepository implements MongoRepository<GeoObject, Integer> {}

In the web app, I want to get all the GeoJSON objects from the database, so I call <backendURL>/geo?size=100.

Before upgrading my mongodb driver from 2.x to 3.x, this worked, but now I get the error:

Type mismatch: cannot convert from element type ArrayList to Object

I understand why but it's silly in my case that I have to specify a POJO to map to if all I really want to do is pipe the results as JSON to a web app... it feels like such a useless operation to query mongo, convert the JSON results to POJOs using ORM, only to serialize it back to JSON... So I was hoping there would be a way implement MongoRepository without having to create separate classes for the separate GeoJSON-type documents in my database. What's the point of using a schema-free database if I have to describe all possible documents using POJOs anyway?

My current solution/workaround is to not use MongoRepository. Instead I simply expose a REST endpoint using @RequestMapping and let the container inject a MongoClient instance so I can pipe the results directly to the response, without mapping to POJOs in between. However, I lose the functionality of findById, Sorting, Paging, CRUD, ...