Failed to process request content for Container Group when LogType is ContainerInstanceLogs

After tested, I found it failed to process request content for Container Group from service side when LogType is ContainerInstanceLogs. Could you help to have a look? Thanks.
Http request:
```
PUT https://management.azure.com/subscriptions/xx-xx-xx-xx/resourceGroups/acctest-cgtest/providers/Microsoft.ContainerInstance/containerGroups/backend

{
"location": "westeurope",
"properties": {
"containers": [
{
"name": "backend",
"properties": {
"image": "microsoft/aci-helloworld",
"command": [],
"ports": [
{
"protocol": "TCP",
"port": 80
}
],
"environmentVariables": [],
"resources": {
"requests": {
"memoryInGB": 1.5,
"cpu": 1
}
}
}
}
],
"restartPolicy": "Always",
"ipAddress": {
"ports": [
{
"protocol": "TCP",
"port": 80
}
],
"type": "Public"
},
"osType": "linux",
"volumes": [],
"diagnostics": {
"logAnalytics": {
"logType": "ContainerInstanceLogs",
"metadata": {},
"workspaceId": "xx-xx-xx-xx",
"workspaceKey": "xxxxxxxxx"
}
}
},
"tags": {}
}
```

Error message:
```
containerinstance.ContainerGroupsClient#CreateOrUpdate: Failure sending request: StatusCode=400 -- Original Error: Code="InvalidRequestContent" Message="The request content was invalid and could not be deserialized: 'Error converting value \"ContainerInstanceLogs\" to type 'System.Nullable`1[Microsoft.Azure.CloudConsole.Providers.Common.Entities.LogAnalyticsLogType]'. Path 'properties.diagnostics.logAnalytics.logType', line 1, position 441.'."
```

Start with the Container Groups PUT request shown in the issue, focusing on properties.diagnostics.logAnalytics.logType and the ContainerInstanceLogs value. Trace the corresponding Azure REST specification and compare its allowed value with the service error; done means the specification and request behavior agree, with a regression check for this payload.

Written by the indexing model from the issue text.