how to pass performance counters to SCOM Retrieve Performance Data Rest API?

Question

I'm trying SCOM Retrieve Performance Data Rest API but I'm unable to pass performance counters as it's unclear in their official documentation.

https://learn.microsoft.com/en-us/rest/api/operationsmanager/data/retrieve%20performance%20data

Example :-

## Get performances for the given server



 $myObject = [PSCustomObject]@{
objectname = 'Memory'
countername = 'Available MBytes'
} 
  $uriPerf = "http://$MS/OperationsManager/data/performance"
    $perfFilter = @"
    {
        "duration": 100,
        "id": "103c21b9-1dd1-e6ff-ede8-1091e0111abc",
        "peformanceCounters":[$myObject]
        
    }"@


    $PerfResponse = Invoke-WebRequest `
        -Method POST `
        -Uri $uriPerf `
        -Body $perfFilter `
        -Headers $scomHeaders `
        -Credential $cred `
        -WebSession $websession `
        #-AllowUnencryptedAuthentication

    $perf = ConvertFrom-Json -InputObject $PerfResponse.Content

    Write-Host "Timestamp after get all get performance data for $($server.id) call $(Get-Date)"
    Write-Host "----------------" 

This is the error I'm getting

 Invoke-WebRequest : {"errorMessage":"Passed parameter cannot be null","errorTrace":""}