Polymorphism Powershell v5 Classes

I have been doing a lot of work lately with Microsoft's Desired State Configuration and creating custom class resources.  As the code is getting more complicated I came accross an instance where I wanted to extend a class to have different implementations put into a list.  After a quick google found no results I thought I would give it a go myself and sure enough it was just like c#

class Foo{
    [string]$SomePram
    Foo([string]$somePram){
        $this.SomePram = $somePram
    }
    [string]GetMessage(){
        return $null
    }
    [void]WriteMessage(){
        Write-Host($this.GetMessage())
    }
}

class Bar : Foo{
    Bar([string]$somePram): base($somePram){

    }
    
    [string]GetMessage(){
        return ("{0} Success" -f $this.SomePram)
    }
}


class Bar2 : Foo{
    Bar2([string]$somePram): base($somePram){

    }
    
    [string]GetMessage(){
        return ("{0} Success" -f $this.SomePram)
    }
}

[Foo[]]$foos = @([Bar]::new("Bar"), [Bar2]::new("Bar2"))

foreach($foo in $foos){
    $foo.WriteMessage()
}