Referenced documents using BI Connector

I’m using MongoDB BI connector starting the mongosqld process in stand alone mode (it generates the schema file ad store it in memory).

The problem is that the structure mapped doesn’t contains in the tables the foreign key columns towards referenced document. For example, below is reported a COLLECTION-A in which a COLLECTION-B is referenced.

The table COLLECTION-A mapped in the schema doesn’t contains the reference to the collectionB.

"_id" : ObjectId("63a172ff55b4250001c59477"),
    "collectionB" : {
        "$ref" : "COLLECTION_B",
        "$id" : ObjectId("5bf7e8c33766cd0001e9578a")

Have you encountered this kind of problem end how you solved it?