MongoDB FDW Problem.

[postgresql@xxxxxxxxxxxx]

My best for all in this list.

i'm trying to use FDW for MongoDB using PostgreSQL 9.4 using pgdg yum 
repo:   yum install postgresql94-server postgresql94-contrib mongo_fdw94
My S.O. is CentOS 9.7 64bits

All is ok with Postgres.  I can create extension, foreign server and 
foreign table.
My problem is when the "columns" of the MongoDB collection are a 
document or array.   In my Foreign Table, I have only null values 
returned in selects.
All of others columns returns its values with no problem.
Can any help or advise me about this?

Thanks a lot!
Lucio - Rio de Janeiro - Brazil

Please see below some info:

On mongo i have this on collection:

{
   "_id" : ObjectId("56ae3a5c2e277c04c77beec7"),
   "address" : {
     "building" : "469",
     "coord" : [-73.961704, 40.662942],
     "street" : "Flatbush Avenue",
     "zipcode" : "11225"
   },
   "borough" : "Brooklyn",
   "cuisine" : "Hamburgers",
   "grades" : [{
       "date" : ISODate("2014-12-30T00:00:00Z"),
       "grade" : "A",
       "score" : 8
     }, {
       "date" : ISODate("2014-07-01T00:00:00Z"),
       "grade" : "B",
       "score" : 23
     }, {
       "date" : ISODate("2013-04-30T00:00:00Z"),
       "grade" : "A",
       "score" : 12
     }, {
       "date" : ISODate("2012-05-08T00:00:00Z"),
       "grade" : "A",
       "score" : 12
     }],
   "name" : "Wendy'S",
   "restaurant_id" : "30112340"
}

On PostgreSQL I have this:

"_id"    "address"    "borough"    "cuisine"    "grades" "name"    
"restaurant_id"
"56ae3a5c2e277c04c77beec7"  <null>  "Brooklyn" "Hamburgers"  <null>   
"Wendy'S"    "30112340"

CREATE FOREIGN TABLE mongo_fdw.restaurants (
   _id NAME NOT NULL,
   address JSON,
   borough VARCHAR,
   cuisine VARCHAR,
   grades VARCHAR, --> errors happens if I put json here
   name VARCHAR,
   restaurant_id VARCHAR
)
SERVER mongo_server
OPTIONS (
   database 'test',
   collection 'restaurants');