`ContainerService/2023-06-02-preview`: agentpools `upgradeSettings` are not cleared when sent empty

[aristosvo]

When I try to cleanup the upgradeSettings by setting an empty object, it returns the previously set values:

PUT /subscriptions/<subscription>/resourceGroups/acctestRG-aks-240113231152069943/providers/Microsoft.ContainerService/managedClusters/acctestaks240113231152069943/agentPools/default?api-version=2023-06-02-preview HTTP/1.1
Host: management.azure.com
User-Agent: Go/go1.21.5 (arm64-darwin) go-autorest/v14.2.1 hashicorp/go-azure-sdk/agentpools/2023-06-02-preview HashiCorp Terraform/1.6.6 (+https://www.terraform.io) Terraform Plugin SDK/2.10.1 terraform-provider-azurerm/acc pid-222c6c49-1b0a-5959-a213-6608f9eb8820
Content-Length: 505
Content-Type: application/json; charset=utf-8
X-Ms-Correlation-Request-Id: 2902ecd6-eee4-48b9-e7d0-ab4f6c93046a
Accept-Encoding: gzip

{"name":"default","properties":{"count":1,"enableAutoScaling":false,"enableCustomCATrust":false,"enableEncryptionAtHost":false,"enableFIPS":false,"enableNodePublicIP":false,"enableUltraSSD":false,"kubeletDiskType":"OS","maxPods":110,"mode":"System","nodeLabels":{},"nodeTaints":[],"orchestratorVersion":"1.27.7","osDiskSizeGB":128,"osDiskType":"Managed","osSKU":"Ubuntu","osType":"Linux","scaleDownMode":"Delete","tags":{},"type":"VirtualMachineScaleSets","upgradeSettings":{},"vmSize":"Standard_DS2_v2"}}
2024/01/13 23:16:35 [DEBUG] AzureRM Response for https://management.azure.com/subscriptions/<subscription>/resourceGroups/acctestRG-aks-240113231152069943/providers/Microsoft.ContainerService/managedClusters/acctestaks240113231152069943/agentPools/default?api-version=2023-06-02-preview: 
HTTP/2.0 200 OK
Azure-Asyncoperation: https://management.azure.com/subscriptions/<subscription>/providers/Microsoft.ContainerService/locations/westeurope/operations/b2956151-18c9-4975-ac27-0cc850714d65?api-version=2017-08-31&t=638407809954864618&c=MIIHHjCCBgagAwIBAgITfwI8HxFJa07lMLGqigAEAjwfETANBgkqhkiG9w0BAQsFADBEMRMwEQYKCZImiZPyLGQBGRYDR0JMMRMwEQYKCZImiZPyLGQBGRYDQU1FMRgwFgYDVQQDEw9BTUUgSW5mcmEgQ0EgMDIwHhcNMjMxMTAxMDc1ODEzWhcNMjQxMDI2MDc1ODEzWjBAMT4wPAYDVQQDEzVhc3luY29wZXJhdGlvbnNpZ25pbmdjZXJ0aWZpY2F0ZS5tYW5hZ2VtZW50LmF6dXJlLmNvbTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAKtktGqbEGyGlhkvok7voYMxDC0FeHV0wbBo3nAJxJGdAbPcPmvqHCx-rXQJaVVwJf3jLIBbyQVMT_v_OfC33iC0jRZJhJKSqrqXNagIPz7vLxOVdkj_6qEOL_fvspPHE0aQlpF8pSQif1-_r7zLzL0vQK9LQHGdUNGbC-O36vI225Q8riiyTk49BNTt8IgTdZEr-jrd8w6M28LLckF4QnwAvMPT5MThfI7f9rQl6RGU92SSFD65TCwMl3yAnaIHD1vWmgNBC-OxQY8iJQxAKpyhYMqqxLKZpEUShARgnOoeexqAJFm7-FFNexPdsEFunO8uuYXvWaNfP77sn5WoQy0CAwEAAaOCBAswggQHMCcGCSsGAQQBgjcVCgQaMBgwCgYIKwYBBQUHAwEwCgYIKwYBBQUHAwIwPQYJKwYBBAGCNxUHBDAwLgYmKwYBBAGCNxUIhpDjDYTVtHiE8Ys-hZvdFs6dEoFggvX2K4Py0SACAWQCAQowggHaBggrBgEFBQcBAQSCAcwwggHIMGYGCCsGAQUFBzAChlpodHRwOi8vY3JsLm1pY3Jvc29mdC5jb20vcGtpaW5mcmEvQ2VydHMvQkwyUEtJSU5UQ0EwMS5BTUUuR0JMX0FNRSUyMEluZnJhJTIwQ0ElMjAwMig0KS5jcnQwVgYIKwYBBQUHMAKGSmh0dHA6Ly9jcmwxLmFtZS5nYmwvYWlhL0JMMlBLSUlOVENBMDEuQU1FLkdCTF9BTUUlMjBJbmZyYSUyMENBJTIwMDIoNCkuY3J0MFYGCCsGAQUFBzAChkpodHRwOi8vY3JsMi5hbWUuZ2JsL2FpYS9CTDJQS0lJTlRDQTAxLkFNRS5HQkxfQU1FJTIwSW5mcmElMjBDQSUyMDAyKDQpLmNydDBWBggrBgEFBQcwAoZKaHR0cDovL2NybDMuYW1lLmdibC9haWEvQkwyUEtJSU5UQ0EwMS5BTUUuR0JMX0FNRSUyMEluZnJhJTIwQ0ElMjAwMig0KS5jcnQwVgYIKwYBBQUHMAKGSmh0dHA6Ly9jcmw0LmFtZS5nYmwvYWlhL0JMMlBLSUlOVENBMDEuQU1FLkdCTF9BTUUlMjBJbmZyYSUyMENBJTIwMDIoNCkuY3J0MB0GA1UdDgQWBBSl-sYW409kjwoQvS1OtNucnmOM0zAOBgNVHQ8BAf8EBAMCBaAwggE1BgNVHR8EggEsMIIBKDCCASSgggEgoIIBHIZCaHR0cDovL2NybC5taWNyb3NvZnQuY29tL3BraWluZnJhL0NSTC9BTUUlMjBJbmZyYSUyMENBJTIwMDIoNCkuY3JshjRodHRwOi8vY3JsMS5hbWUuZ2JsL2NybC9BTUUlMjBJbmZyYSUyMENBJTIwMDIoNCkuY3JshjRodHRwOi8vY3JsMi5hbWUuZ2JsL2NybC9BTUUlMjBJbmZyYSUyMENBJTIwMDIoNCkuY3JshjRodHRwOi8vY3JsMy5hbWUuZ2JsL2NybC9BTUUlMjBJbmZyYSUyMENBJTIwMDIoNCkuY3JshjRodHRwOi8vY3JsNC5hbWUuZ2JsL2NybC9BTUUlMjBJbmZyYSUyMENBJTIwMDIoNCkuY3JsMBcGA1UdIAQQMA4wDAYKKwYBBAGCN3sBATAfBgNVHSMEGDAWgBSuecJrXSWIEwb2BwnDl3x7l48dVTAdBgNVHSUEFjAUBggrBgEFBQcDAQYIKwYBBQUHAwIwDQYJKoZIhvcNAQELBQADggEBAExIYXdFVUapZo362HDQaHc6wGx13EzUO_411uqdB2iCcu5lM5hkBwSQcGR4lbIbB5Ia5YeXXATbMOc_vUNBXKXHcEjJeuHfpLq2fCHyToYeka2qRzeqssG9kg7E2Pk2flpZiPO8MAapWLjcYVivLTaBePD7JQ6ndKjYDhyO3lTlCmZQtXao95RI5Iidu2TuESDDnfq7quBHQvTNke6tuLsJD3ziC6pm8rgvYIGv6gZ0sVVxnKiRgMrTzyzJPPQK_stiGxSJL-cWZvU7tQLO9AAyk0wRok3_wc5GeWr9r4cMcl7bA0rtiLwBkgPgOYjWkES0RKReb9cmIdjwnneKsVg&s=M9dDOrCRNXc3AQtDhMTtA3Okd0__S9MeoZb5b7VUuyTH0a2XOiztZJCt-YRXq57wsJzl51KXDH7CTy7vsIJUUHKiD-8oGBTekEr0-Axk0TaS7jB0fnpdx1o-CWprm0_KAELpA0u7LxP6fq_87--w2qqoAaTXzQAELun1vkTSTJIKXiLd_5dY-Hn8L6r7_m2xLnxyOl8-EjRRnlwYV8vzv3qnqyQfmJtHDvWP7A4uKeGEyULIW4Nwx9xXGLaKRbRRGL0KRTdQRRxloS4Imk8XUKU05-nuJp9Cnpjur6uEldkE1z9jeYsP6F53XVE3j9g6Yr5BXdOz_OZwVzWqEq7V9g&h=FsuEALtAIO-SkI6LXZVCl16akCyqUrWg8Px6F711svA
Cache-Control: no-cache
Content-Type: application/json
Date: Sat, 13 Jan 2024 22:16:35 GMT
Expires: -1
Pragma: no-cache
Strict-Transport-Security: max-age=31536000; includeSubDomains
Vary: Accept-Encoding
X-Content-Type-Options: nosniff
X-Ms-Correlation-Request-Id: 2902ecd6-eee4-48b9-e7d0-ab4f6c93046a
X-Ms-Ratelimit-Remaining-Subscription-Writes: 1199
X-Ms-Request-Id: b2956151-18c9-4975-ac27-0cc850714d65
X-Ms-Routing-Request-Id: WESTEUROPE:20240113T221635Z:bfdbb5b3-7cb8-476a-a6e0-01bb3f18d080

{
  "id": "/subscriptions/<subscription>/resourcegroups/acctestRG-aks-240113231152069943/providers/Microsoft.ContainerService/managedClusters/acctestaks240113231152069943/agentPools/default",
  "name": "default",
  "type": "Microsoft.ContainerService/managedClusters/agentPools",
  "properties": {
   "count": 1,
   "vmSize": "Standard_DS2_v2",
   "osDiskSizeGB": 128,
   "osDiskType": "Managed",
   "kubeletDiskType": "OS",
   "maxPods": 110,
   "type": "VirtualMachineScaleSets",
   "enableAutoScaling": false,
   "scaleDownMode": "Delete",
   "provisioningState": "Updating",
   "powerState": {
    "code": "Running"
   },
   "orchestratorVersion": "1.27.7",
   "currentOrchestratorVersion": "1.27.7",
   "enableNodePublicIP": false,
   "enableCustomCATrust": false,
   "mode": "System",
   "enableEncryptionAtHost": false,
   "enableUltraSSD": false,
   "osType": "Linux",
   "osSKU": "Ubuntu",
   "nodeImageVersion": "AKSUbuntu-2204gen2containerd-202312.06.0",
   "upgradeSettings": {
    "maxSurge": "2",
    "drainTimeoutInMinutes": 40
   },
   "enableFIPS": false,
   "securityProfile": {
    "sshAccess": "LocalUser"
   }
  }
 }

Reproduction can be found in this azurerm PR.