message: Adding customSubDomainName property.
diff: "internalId": {
  "type": "string",
  "description": "The internal identifier."
  + },
  + "customSubDomainName": {
  + "type": "string",
  + "description": "Optional subdomain name used for token-based authentication."
  }
  },
  "description": "Properties of Cognitive Services account."
  