Azure ARM templates - empty values as a parameters, IF function - azure-resource-manager

Question

I am preparing ARM template for "Schedule update deployment" in Update Management service. I want to add parameters like: "excludedKbNumbers" and "includedKbNumbers". I am deploying my templates using powershell. When I am passing KB numbers using mentioned parameters templates completed successfully. In case when I am putting KB number using one of the mentioned parameters, second is empty, template completed successfully. Problem is when I dont want to pass Included/Exluded KB numbers, in my powershell deployment command I am not putting parameter names "excludedKbNumbers" and "includedKbNumbers", and then I am receiving below error: "message": "{\"Message\":\"The request is invalid.\",\"ModelState\":{\"softwareUpdateConfiguration.properties.updateConfiguration\":[\"Software update configuration has same KbNumbers in
includedKbNumbers and excludedKbNumbers.\"]}}"
I am using this structure in my template json('null') and this is a problematic area.
extract from my template:
"parameters": {
"excludedKbNumbers": {
"type": "string",
"defaultValue": "",
"metadata": {
"description": "Specify excluded KB numbers, required data structure: 123456"
}
},
"includedKbNumbers": {
"type": "string",
"defaultValue": "",
"metadata": {
"description": "Specify included KB numbers, required data structure: 123456"
}
},
"resources": [
{
"type": "Microsoft.Automation/automationAccounts/softwareUpdateConfigurations",
"apiVersion": "2017-05-15-preview",
"name": "[concat(parameters('automationAccountName'), '/', parameters('scheduleName'))]",
"properties": {
"updateConfiguration": {
"operatingSystem": "[parameters('operatingSystem')]",
"windows": {
"includedUpdateClassifications": "[parameters('Classification')]",
"excludedKbNumbers": [
"[if(empty(parameters('excludedKbNumbers')), json('null'), parameters('excludedKbNumbers'))]"
],
"includedKbNumbers": [
"[if(empty(parameters('includedKbNumbers')), json('null'), parameters('includedKbNumbers'))]"
],
"rebootSetting": "IfRequired"
},
"targets": {
"azureQueries": [
{
"scope": [
"[concat('/subscriptions', '/', parameters('subscriptionID'))]"
],
"tagSettings": {
"tags": {
"[parameters('tagKey')]": [
"[parameters('tagValue')]"
]
},
"filterOperator": "All"
},
"locations": []
}
]
},
"duration": "PT2H"
},
"tasks": {},
"scheduleInfo": {
"isEnabled": false,
"startTime": "2050-03-03T13:10:00+01:00",
"expiryTime": "2050-03-03T13:10:00+01:00",
"frequency": "OneTime",
"timeZone": "Europe/Warsaw"
}
}
}
],

Answer 1

try doing this:
"excludedKbNumbers": "[if(empty(parameters('excludedKbNumbers')), json('null'), array(parameters('excludedKbNumbers')))]",
"includedKbNumbers": "[if(empty(parameters('includedKbNumbers')), json('null'), array(parameters('includedKbNumbers')))]"