@PowerShell/powershell-committee discussed #2544 and decided that we should fix all the cmdlets except for the Provider ones as it's a risky breaking change as we can't be certain if $null is a valid value for the path.

• Get-Credential -UserName
• Get-Event -SourceIdentifier
• Get-EventSubscriber -SourceIdentifier
• Get-Help -Name
• Get-PSBreakpoint -Script
• Get-PSProvider -PSProvider
• Get-PSSessionConfiguration -Name
• Get-PSSnapin -Name
• Get-Runspace -Name
• Get-RunspaceDebug -RunspaceName
• Get-Service -Name
• Get-TraceSource -Name
• Get-Variable -Name
• Get-WmiObject -Class
• Get-WmiObject -Property