PowerShell, Bouncy Castle and Subject Alternative Names

function Add-SubjectAlternativeName
{
[CmdletBinding()]
param(
    [Parameter(Mandatory = $true, ValueFromPipeline = $true)]
    [Org.BouncyCastle.X509.X509V3CertificateGenerator] $CertificateGenerator,

    [Parameter(Mandatory = $true)]
    [string[]] $DnsName
)

    $names = $DnsName |
        foreach {
            New-Object Org.BouncyCastle.Asn1.X509.GeneralName(
                [Org.BouncyCastle.Asn1.X509.GeneralName]::DnsName, $_)
            }

    $extension = New-Object Org.BouncyCastle.Asn1.DerSequence($names)

    $CertificateGenerator.AddExtension(
        [Org.BouncyCastle.Asn1.X509.X509Extensions]::SubjectAlternativeName.Id,
        $false,
        $extension)

    return $CertificateGenerator
}