message: Fix swagger issue: add missing etag
diff: "type": "string",
  "description": "Id of private endpoint connection."
  },
  + "etag": {
  + "type": "string",
  + "description": "Modified whenever there is a change in the state of private endpoint connection."
  + },
  "properties": {
  "$ref": "#/definitions/PrivateEndpointConnectionProperties",
  "x-ms-client-flatten": true,
  