message: eventgrid: fixing the identity type
  The documentation states this supports `SystemAssigned, UserAssigned` however this value isn't specified
diff: "description": "The type of managed identity used. The type 'SystemAssigned, UserAssigned' includes both an implicitly created identity and a set of user-assigned identities. The type 'None' will remove any identity.",
  "enum": [
  "SystemAssigned",
  + "SystemAssigned, UserAssigned",
  "UserAssigned"
  ],
  "type": "string",
  