public/Get-VSAPatchMissing.ps1

function Get-VSAPatchMissing {
    <#
    .Synopsis
       Returns an array of missing patches.
    .DESCRIPTION
       Returns an array of missing patches on an agent machine, with denied patches either included or excluded.
       Takes either persistent or non-persistent connection information.
    .PARAMETER VSAConnection
        Specifies existing non-persistent VSAConnection.
    .PARAMETER URISuffix
        Specifies URI suffix if it differs from the default.
    .PARAMETER AgentId
        Specifies id of agent machine.
    .PARAMETER Parallel
        Fetches the remaining pages of a large collection concurrently instead of one after another.
        Opt-in: without it, behaviour is unchanged. Results are identical either way (same records,
        merged in $skip order). Only engages once the collection is large enough to be worth it
        (see -ParallelThreshold).
    .PARAMETER ThrottleLimit
        Maximum number of concurrent requests when -Parallel is used (default 8). On shared SaaS you
        are one tenant among many, so a modest value is a good citizen; the engine also reduces
        concurrency automatically if the server returns HTTP 429, then recovers.
    .PARAMETER ParallelThreshold
        Minimum total record count before -Parallel actually engages. 0 (default) means automatic:
        two full throttle windows, i.e. 2 * ThrottleLimit * 100 records. Below that the sequential
        path is used, because it is faster than paying to set up extra connections. .EXAMPLE
       Get-VSAPatchMissing -AgentId 979868787875855
    .PARAMETER Filter
        Specifies REST API Filter.
    .PARAMETER Sort
        Specifies REST API Sorting.
    .PARAMETER HideDeniedPatches
        Excludes patches that have been denied from the result.
    .EXAMPLE
       Get-VSAPatchMissing -AgentId 979868787875855 -HideDeniedPatches
    .EXAMPLE
       Get-VSAPatchMissing -VSAConnection $connection -AgentId 979868787875855
    .INPUTS
       Accepts piped non-persistent VSAConnection
    .OUTPUTS
       Array of items that represent missing patches
    #>


    [CmdletBinding()]
    param (
        [parameter(Mandatory = $false,
            ValueFromPipelineByPropertyName = $true)]
        [ValidateNotNull()]
        [VSAConnection] $VSAConnection,

        [parameter(DontShow, Mandatory=$false)]
        [ValidateNotNullOrEmpty()]
        [string] $URISuffix = 'api/v1.0/assetmgmt/patch/{0}/machineupdate/{1}',

        [parameter(Mandatory = $true,
            ValueFromPipelineByPropertyName = $true)]
        [ValidateScript({
            if( $_ -notmatch "^\d+$" ) {
                throw "Non-numeric Id"
            }
            return $true
        })]
        [string] $AgentID,

        [parameter(Mandatory=$false,
            ValueFromPipelineByPropertyName=$true)]
        [ValidateNotNullOrEmpty()]
        [string] $Filter,

        [parameter(Mandatory=$false,
            ValueFromPipelineByPropertyName=$true)]
        [ValidateNotNullOrEmpty()]
        [string] $Sort,

        [Parameter(Mandatory = $false)]
        [switch] $HideDeniedPatches,

        # Opt-in parallel paging for large collections (see Invoke-VSARestMethod). No effect on small
        # ones: below -ParallelThreshold the sequential path is used.
        [parameter(Mandatory = $false)]
        [switch] $Parallel,

        [parameter(Mandatory = $false)]
        [ValidateRange(1, 64)]
        [int] $ThrottleLimit = 8,

        [parameter(Mandatory = $false)]
        [ValidateRange(0, [int]::MaxValue)]
        [int] $ParallelThreshold = 0
    )
    process {

    [hashtable]$Params = @{
        URISuffix     = $( $URISuffix -f $AgentID, $HideDeniedPatches.ToString() )
        VSAConnection = $VSAConnection
        Filter        = $Filter
        Sort          = $Sort
    }

    foreach ( $key in @($Params.Keys)  ) {
        if ( -not $Params[$key]) { $Params.Remove($key) }
    }

    # Forward the opt-in parallel controls to the shared read path, which owns the paging engine.
    if ($Parallel) {
        $Params['Parallel']      = $true
        $Params['ThrottleLimit'] = $ThrottleLimit
        if ($ParallelThreshold -gt 0) { $Params['ParallelThreshold'] = $ParallelThreshold }
    }
    return Invoke-VSARestMethod @Params
    }
}
New-Alias -Name Get-VSAMissingPatches -Value Get-VSAPatchMissing
Export-ModuleMember -Function Get-VSAPatchMissing -Alias Get-VSAMissingPatches