Validate Azure resource move with REST API

# https://docs.microsoft.com/en-us/azure/azure-resource-manager/resource-group-move-resources#validate-move
 
# Provide your source subscription id
$subscriptionid = "sourcesubid"
#Provide the Resource Group Name containing your source resources
$resourcegroup = "source resource group name"
# Provide your target subscription id (could be the same as source)
$targetsub = "targetsubid"
# Provide your target resource group name (it must exist in advance)
$targetrgname = "target resource group name"
 
# Select the source subscription, so we can dynamically get a list of resources
Select-AzSubscription $subscriptionid
# Get all resources within the source resource group
$resourceids = get-azresource -resourcegroupname $resourcegroup
# Remove resource types that we know are incompatible with the move operation.
# We will delete these resources before migration, so lets remove them from the object array
$resourceids = $resourceids | Where-Object { $_.ResourceType `
        -notlike "*/configurations" ` # Validation throws errors of 'Not top-level resource', because this is contained within Automation Account
        -and $_.ResourceType -notlike "*/runbooks" ` # Validation throws errors of 'Not top-level resource', because this is contained within Automation Account
        -and $_.ResourceType -notlike "*/extensions*" ` # Validation throws errors of 'Not top-level resource', because this is contained within Virtual Machine
        -and $_.ResourceType -notlike "*/applicationgateways*" `
        -and $_.ResourceType -notlike "*/publicipaddresses*" `
        -and $_.ResourceType -notlike "*/vaults*" `
        -and $_.ResourceType -notlike "*/connections*" ` # Excluding Connections because they're part of the VPN GW which will be deleted
        -and $_.ResourceType -notlike "*/localnetworkgateways*" ` # Excluding Local Network Gateways because they're part of the VPN GW which will be deleted
        -and $_.ResourceType -notlike "*/virtualnetworkgateways*" ` # Excluding VPNGW because it depends on Public IP address resource which cannot be move. 
}
#Convert our array to JSON to pass into the body
$resourceids = $resourceids.resourceid | ConvertTo-JSON
 
# Get our bearer token because we're already signed into Azure
. .\Get-AzCachedAccessToken.ps1 #https://gallery.technet.microsoft.com/scriptcenter/Easily-obtain-AccessToken-3ba6e593
$BearerToken = ('Bearer {0}' -f (Get-AzCachedAccessToken))
$RequestHeader = @{
    "Content-Type"  = "application/json";
    "Authorization" = "$BearerToken"
}
# Build the Body variable, using our $resourceids array
$Body = @"
{
 "resources": $resourceids,
 "targetResourceGroup": "/subscriptions/$targetsub/resourceGroups/$targetrgname"
}
"@
 
$URI = "https://management.azure.com/subscriptions/$subscriptionid/resourceGroups/$resourcegroup/validateMoveResources?api-version=2019-05-10"
$response = Invoke-WebRequest -Uri $URI -Method POST -body $body -header $RequestHeader
 
# Wait a while for the validation job to complete
Sleep 30
 
# From the returned response, find the Location section of the string and extract it
$a = $response.rawcontent
$checkURI = $a.Substring($a.IndexOf('https:'), $a.IndexOf('Retry-After:')-$a.IndexOf('https:'))
$CheckResponse = Invoke-WebRequest -Uri $checkURI -Method Get -header $RequestHeader