関連ワード:  powershell check if object is null    powershell check if object is null or empty    powershell check if item is null    powershell check if object is empty    powershell check if object is not null    powershell check if json object is empty    powershell check if system object is empty    powershell check if custom object is empty    powershell check if object array is empty    powershell check if object property is empty