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db.collection.aggregate([{$project:{"modules":{"$objectToArray":"$MODULES"}}},{"$unwind":"$modules"},{"$project":{"types":{"$objectToArray":"$modules.v.PARAMS"},xname:"$modules.v.XNAME"}},{$unwind:"$types"},{$group:{"_id":null,"xname":{"$addToSet":"$xname"},"types":{"$addToSet":"$types.v.TYPE"},}}])