powershell get sql virtual

Hello,

When I execute this powershell function :

function Get-ClusterSQL
{
    param($cluster)
   
    gwmi -class "MSCluster_Resource" -namespace "root\mscluster" -computername $cluster  | where {$_.type -eq "SQL Server"} | Select @{n='VirtualServerName';e={$_.PrivateProperties.VirtualServerName}}, @{n='InstanceName';e={$_.PrivateProperties.InstanceName}}, `
    @{n='ServerInstance';e={("{0}\{1}" -f $_.PrivateProperties.VirtualServerName,$_.PrivateProperties.InstanceName).TrimEnd('\')}}
   
}

The result is

VirtualServerName                       InstanceName                            ServerInstance
-----------------                       ------------                            --------------
Test                                    Test12                                  Test\Test12

How can I modify the function for having the result test\test12?

Thanks

Regards

bibi