Applying HSTS settings using WebAdministrationDsc/WebConfigPropertyCollection?

I'm using Windows Server 2019, Posh5.1, WebAdministrationDsc 4.1.0, and WebConfigPropertyCollection. I see I have to use 2 passes for the resource to do this way for multiple properties, so I populate an array in my psd1 data file then iterate over the collection like below, where I've seen comments in the issues github that this is the way. https://github.com/dsccommunity/WebAdministrationDsc/issues/534

("HttpCustomHeaderSts","IIS:\Sites\Default Web Site","system.applicationHost/sites","site","hsts","enabled","true","includeSubDomains","true","Present"),
                                                        ("HttpCustomHeaderSts2","IIS:\Sites\Default Web Site","system.applicationHost/sites/site","site","hsts","enabled","true","redirectHttpToHttps","true","Present"),
                                                        
$ConfigurationData.NonNodeData.Roles.([String]($Node.Role -eq "WEB")).ConfigColls.foreach({
            WebConfigPropertyCollection $_[0]
            {
                WebsitePath       = $_[1]
                Filter            = $_[2]
                CollectionName    = $_[3]
                ItemName          = $_[4]
                ItemKeyName       = $_[5]
                ItemKeyValue      = $_[6]
                ItemPropertyName  = $_[7]
                ItemPropertyValue = $_[8]
                Ensure            = $_[9]
            }
        })

But I get:

Exception calling GetAddElementSchema with 1 argument(s): Invalid index.

Never mind. Rookie mistake on my end, where I didn't include the full error. This code 0x80070585 maps to The element specified by bstrElementName cannot be found. I stepped through the resource to hit that dead-end. I'll submit an edit, but I'm writing my own resource to do this that I'll provide. If you want to use though you'd need to append it to a library you don't use or create your own generic collection. I have one called xUtilityDsc I throw stuff like this into.

This seems to do the trick. First it's your schema.mof then the code.

[ClassVersion("1.0.0.0"), FriendlyName("xIisHsts")]
class xIisHsts : OMI_BaseResource
{
    [Key] String Site;
    [Write] Boolean Enabled;
    [Write] Boolean RedirectHttpToHttps;
    [Write] Boolean IncludeSubDomains;
    [Write] Boolean Preload;
    [Write] UInt32 Maxage;
    [Write, ValueMap{"Present","Absent"}, Values{"Present","Absent"}] String Ensure;
};

Now Psm1 content:

<#
    .SYNOPSIS
        Returns HSTS settings for a passed in site name.

    .PARAMETER Site
        Site's hsts status.
#>
#Get-TargetResource "Default Web Site"
function Get-TargetResource
{
    [CmdletBinding()]
    [OutputType([System.Collections.Hashtable])]
    param
    (
        # Name of the Firewall Rule
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [String]
        $Site
    )
    $siteElement = Get-IISConfigCollectionElement -ConfigCollection $sitesCollection -ConfigAttribute @{"name"=$Site} 
    return $hstsElement = Get-IISConfigElement -ConfigElement $siteElement -ChildElementName "hsts" 
}

#Set-TargetResource -Site "Default Web Site" -Enabled $true -maxage 31536000 -redirectHttpToHttps $true -includeSubDomains $true -Ensure "Present" -preload $true
function Set-TargetResource
{
    [CmdletBinding()]
    [OutputType([System.Collections.Hashtable])]
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [Boolean]
        $Enabled,
        
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [String]
        $Site,

        [System.UInt32]
        $maxage,

        [Boolean]
        $redirectHttpToHttps,

        [Boolean]
        $includeSubDomains,

        [Boolean]
        $preload,

        [Parameter(Mandatory = $true)]
        [ValidateSet("Present","Absent")]
        [System.String]
        $Ensure
    )
    Import-Module WebAdministration
    If ($Ensure -eq "Absent")
    {
        Try{
            Start-IISCommitDelay
            $sitesCollection = Get-IISConfigSection -SectionPath "system.applicationHost/sites" | Get-IISConfigCollection 
            $siteElement = Get-IISConfigCollectionElement -ConfigCollection $sitesCollection -ConfigAttribute @{"name"=$Site} 
            $hstsElement = Get-IISConfigElement -ConfigElement $siteElement -ChildElementName "hsts" | Remove-IISConfigElement -Confirm:$false
            Stop-IISCommitDelay
        }
        catch{
                
        }
        finally{
            Write-Verbose "HSTS Failed"
                
        }
    }
    else
    {
        Try{
            Start-IISCommitDelay
            $sitesCollection = Get-IISConfigSection -SectionPath "system.applicationHost/sites" | Get-IISConfigCollection 
            $siteElement = Get-IISConfigCollectionElement -ConfigCollection $sitesCollection -ConfigAttribute @{"name"=$Site} 
            $hstsElement = Get-IISConfigElement -ConfigElement $siteElement -ChildElementName "hsts" 
            Set-IISConfigAttributeValue -ConfigElement $hstsElement -AttributeName "max-age" -AttributeValue $maxage
            Set-IISConfigAttributeValue -ConfigElement $hstsElement -AttributeName "includeSubDomains" -AttributeValue $includeSubDomains
            Set-IISConfigAttributeValue -ConfigElement $hstsElement -AttributeName "preload" -AttributeValue $preload
            Set-IISConfigAttributeValue -ConfigElement $hstsElement -AttributeName "redirectHttpToHttps" -AttributeValue $redirectHttpToHttps
            Set-IISConfigAttributeValue -ConfigElement $hstsElement -AttributeName "enabled" -AttributeValue $Enabled
            Stop-IISCommitDelay
        }
        catch{
        }
        finally{
            Write-Verbose "HSTS Failed"
        }
    }
}

#Test-TargetResource -Site "Default Web Site" -Enabled $true -maxage 31536000 -redirectHttpToHttps $true -includeSubDomains $true -Ensure "Present" -preload $true

<#
    .SYNOPSIS
        Tests HSTS settings for a passed in site name.

    .PARAMETER Site
        Site's hsts status.
#>
function Test-TargetResource
{
    [CmdletBinding()]
    [OutputType([System.Collections.Hashtable])]
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [Boolean]
        $Enabled,
        
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [String]
        $Site,

        [System.UInt32]
        $maxage,

        [Boolean]
        $redirectHttpToHttps,

        [Boolean]
        $includeSubDomains,

        [Boolean]
        $preload,

        [Parameter(Mandatory = $true)]
        [ValidateSet("Present","Absent")]
        [System.String]
        $Ensure
    )
    Import-Module WebAdministration
    [bool]$valid = $true
    $butes = Get-IISConfigElement -ConfigElement (Get-IISConfigCollectionElement -ConfigCollection (Get-IISConfigSection -SectionPath "system.applicationHost/sites" | Get-IISConfigCollection) -ConfigAttribute @{"name"=$Site}) -ChildElementName "hsts" 
    if ($Ensure -eq "Absent" -and (![string]::IsNullOrWhiteSpace($butes.ElementTagName)))
    {
        $valid= $false
    }
    
    $butes.Attributes.ForEach({
        if ($valid)
        {
            #write-host "name:$($_.name) value:$($_.value)"
            if ($_.name -eq 'enabled'-and $_.value -ne $Enabled){$valid=$false}
            if ($_.name -eq "max-age" -and $_.value -ne $maxage){$valid=$false}
            if ($_.name -eq "redirectHttpToHttps" -and $_.value -ne $redirectHttpToHttps){$valid=$false}
            if ($_.name -eq "includeSubDomains" -and $_.value -ne $includeSubDomains){$valid=$false}
            if ($_.name -eq "preload" -and $_.value -ne $preload){$valid=$false}
        }
    })
    
    #write-host $valid
    If ($valid)
    {$true}
    else
    {$false}

}

Export-ModuleMember -Function *-TargetResource