message: Fix upgrade policy and mark issuer as required
diff: },
  "required": [
  "isAdmin",
  - "certificateCommonName"
  + "certificateCommonName",
  + "certificateIssuerThumbprint"
  ]
  },
  "ClusterEnvironment": {
  "items": {
  "$ref": "#/definitions/NodeTypeDescription"
  }
  + },
  + "upgradeDescription": {
  + "description": "The policy to use when upgrading the cluster.",
  + "$ref": "#/definitions/ClusterUpgradePolicy"
  }
  }
  },
  