Pro-Exchange: Meeting Room scheduling problems after installing Exchange 2010 SP2 RU 5v2

Thanks to Timmy L for reporting this

After installing Exchange 2010 SP2 RU 5v2 all of a sudding meeting request while inviting Meeting Rooms as a Resource get declined all the time.

After some investigation the Update has changed all Room Mailbox Reource In-Policy Requests to Selected Recipients and a blank list for no reason at all.

Changing the settings back to All Users resolves the problem.

The Rooms accepts booking again

Unfortunately if you have to do that for 100+ meeting rooms this is a time consuming exercise.
Luckily for us Exchange Admins this can be automated easily with a Powershell one liner

Get-Mailbox | where {$_.RecipientTypeDetails -eq "Room"} | Set-CalendarProcessing -AllBookInPolicy $True