Botservices definition doesnt match the api calls made by portal for v4

When we create a new bot in portal with the portal makes call to management.azure.com with arm template which shows following section in properties section of resource of type("Microsoft.BotService/botServices")
"parameters": "[union(deployment().properties.parameters, json(concat('{\"tenant\":{\"value\":\"', subscription().tenantId, '\"}}')), json(concat('{\"stateStorage\":{\"value\":\"DefaultEndpointsProtocol=https;AccountName=',parameters('storageAccountName'),';AccountKey=',listkeys(variables('storageAccountId'), '2015-05-01-preview').key1,';\"}}')))]",

that field is not provided in this json definition, why?

https://github.com/Azure/azure-rest-api-specs/blob/master/specification/botservice/resource-manager/Microsoft.BotService/preview/2018-07-12/botservice.json

Start with specification/botservice/resource-manager/Microsoft.BotService/preview/2018-07-12/botservice.json and compare its botServices properties with the ARM template section and portal call described in the issue. Determine whether the parameters field belongs in this API definition, then verify the expected representation against the surrounding specification before proposing the correction.

Written by the indexing model from the issue text.