Fixed order (#15367)

C# needs required fields to be before any optional fields. Because username and password are no longer required, autorest is ordering these parameters alphabetically.

Author: paterasMSFT

specification/batch/resource-manager/Microsoft.Batch/stable/2021-06-01/BatchManagement.json

@@ -4258,11 +4258,6 @@
     "ContainerRegistry": {
       "type": "object",
       "properties": {
-        "registryServer": {
-          "type": "string",
-          "title": "The registry URL.",
-          "description": "If omitted, the default is \"docker.io\"."
-        },
         "username": {
           "type": "string",
           "x-ms-client-name": "userName",
@@ -4272,6 +4267,11 @@
           "type": "string",
           "title": "The password to log into the registry server."
         },
+        "registryServer": {
+          "type": "string",
+          "title": "The registry URL.",
+          "description": "If omitted, the default is \"docker.io\"."
+        },
         "identityReference": {
           "title": "The reference to the user assigned identity to use to access an Azure Container Registry instead of username and password.",
           "$ref": "#/definitions/ComputeNodeIdentityReference"