Kubernetes Cluster Node Pool API shouldn't switch the key of node label as lower case

[neil-yechenwei]

After tested, I found Kubernetes Cluster Node Pool API would switch the key of node label as lower case. I assume it shouldn't switch it to lower case.

Http request call:

PUT https://management.azure.com/subscriptions/xx-xx-xx-xx/resourceGroups/acctestRG-aks-test02/providers/Microsoft.ContainerService/managedClusters/acctestakstest02/agentPools/kubepool02

{
    "properties": {
        "count": 1,
        "enableAutoScaling": false,
        "enableNodePublicIP": false,
        "mode": "User",
        "nodeLabels": {
            "serverGroupName": "testServerGroup"
        },
        "osType": "Linux",
        "scaleSetPriority": "Regular",
        "tags": {},
        "type": "VirtualMachineScaleSets",
        "vmSize": "Standard_DS2_v2"
    }
}

Response:

[alikhtag]

this causing issues for us in terraform, would be nice to get it resolved :slightly_smiling_face:

[ghost]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @qike-ms, @jwilder, @thomas1206, @seanmck.

Issue Details

---

After tested, I found Kubernetes Cluster Node Pool API would switch the key of node label as lower case. I assume it shouldn't switch it to lower case. Http request call: ``` PUT https://management.azure.com/subscriptions/xx-xx-xx-xx/resourceGroups/acctestRG-aks-test02/providers/Microsoft.ContainerService/managedClusters/acctestakstest02/agentPools/kubepool02 { "properties": { "count": 1, "enableAutoScaling": false, "enableNodePublicIP": false, "mode": "User", "nodeLabels": { "serverGroupName": "testServerGroup" }, "osType": "Linux", "scaleSetPriority": "Regular", "tags": {}, "type": "VirtualMachineScaleSets", "vmSize": "Standard_DS2_v2" } } ``` Response: 

Author:	neil-yechenwei
Assignees:	MyronFanQiu
Labels:	`Container Service`, `Service Attention`, `needs-triage`
Milestone:	-