PowerShell function: Remove-Null - https://stackoverflow.com/questions/33038848/how-to-exclude-non-valued-object-properties-when-converting-to-json-in-powershel/63946256#63946256

Remove-Null.ps1

<#
.SYNOPSIS
	Removes null property values from objects.
.DESCRIPTION
	Removes property values that are null (or empty, unless -LeaveEmptyStrings parameter is use) from an object or array of objects. Additional items may be removed if they are passed as input to the -AlsoRemove parameter.
.EXAMPLE
	[pscustomobject]@{Number=1;String="Test";Empty="";Null=$null} | Remove-Null

	Number String
	------ ------
	     1 Test  

	Creates a custom object including empty/null values and then removes the null and empty values from the output object.
.EXAMPLE
	[pscustomobject]@{Number=1;String="Test";Empty="";Null=$null} | Remove-Null -LeaveEmptyStrings -AlsoRemove "Test"

	Number Empty
	------ -----
	     1 

	Creates a custom object with empty/null values and then removes the null value and a specified value from the the output object.
.EXAMPLE
	Get-CimInstance -ClassName Win32_UserProfile | Remove-Null -AlsoRemove 'Win32_FolderRedirectionHealth' | Select -First 2 | Format-Table

	HealthStatus LastUseTime           Loaded LocalPath               RoamingConfigured SID
	------------ -----------           ------ ---------               ----------------- ---                                   
	           3 9/18/2020 10:44:11 AM   True C:\Users\DefaultAppPool             False S-1-5-82-3006700770-424185619-1745488…
	           3 9/18/2020 10:44:11 AM   True C:\Users\Administrator              False S-1-5-21-540089215-2089150192-1846166…

	Gets an array of CimInstance objects for Win32_UserProfiles and outputs an object with all property removed that are null, empty, consist of the string "Win32_FolderRedirectionHealth", or the ToString() method results with "Win32_FolderRedirectionHealth".
.INPUTS
	System.Object or System.Object[]
		You can pipe an object or array of objects to Remove-Null.
.OUTPUTS
	System.Management.Automation.PSCustomObject or System.Object[]
		Returns either a single object, or a collection of objects, corresponding to the input.
#>
Function Remove-Null {
	[CmdletBinding()]
	Param(
		# Object from which to remove the null values.
		[Parameter(ValueFromPipeline,Mandatory)]
		$InputObject,
		# Instead of also removing values that are empty strings, include them in the output.
		[Switch]$LeaveEmptyStrings,
		# Additional entries to remove, which are either present in the properties list as an object or as a string representation of the object.
		# I.e. $item.ToString().
		[Object[]]$AlsoRemove=@()
	)
	Process {
		# Iterate InputObject in case input was passed as an array
		ForEach ($obj in $InputObject) {
			$obj | Select-Object -Property (
				$obj.PSObject.Properties.Name | Where-Object {
					-not (
						# If the property is null, remove it
						$null -eq $obj.$_ -or
                                                # If -LeaveEmptyStrings is not specified and the property is an empty string, remove it
                                                (-not $LeaveEmptyStrings.IsPresent -and [string]::IsNullOrEmpty($obj.$_)) -or
						# If AlsoRemove contains the property, remove it
						$AlsoRemove.Contains($obj.$_) -or
						# If AlsoRemove contains the string representation of the property, remove it
						$AlsoRemove.Contains($obj.$_.ToString())
					)
				}
			)
		}
	}
}