mutation SetMarketplaceOfferMaxQuantity($request: SetMarketplaceOfferMaxQuantityCommandRequestInput!) {
  SetMarketplaceOfferMaxQuantity(request: $request)
}

{
  "request": {
    "offerKeys": [
      "id"
    ],
    "maxQuantity": "value"
  }
}

{
  "data": {
    "SetMarketplaceOfferMaxQuantity": true
  }
}