mutation AddItemVariationValue($request: AddItemVariationValueCommandRequestInput!) {
  AddItemVariationValue(request: $request) {
    variationValueId
  }
}

{
  "request": {
    "itemId": "id",
    "variationId": "id",
    "variationValue": {
      "descriptions": [
        {
          "languageIso": "string",
          "name": "string"
        }
      ]
    }
  }
}

{
  "data": {
    "AddItemVariationValue": {
      "variationValueId": "id"
    }
  }
}