message: Add vendorExtension for empty response
  check for x-isEmpty and add the json:true option  - to allow the RequestEmpty to pass a JSON object in the body.
diff: @@ -4674,7 +4674,7 @@ export class AccountingApi {
  qs: localVarQueryParameters,
  headers: localVarHeaderParams,
  uri: localVarPath,
  - useQuerystring: this._useQuerystring,
  + useQuerystring: this._useQuerystring,json: true,
  body: ObjectSerializer.serialize(requestEmpty, "RequestEmpty")
  };
  