Filter for In-place hold

Is there any way to get a server-side list of all mailboxes with In-Place holds applied? For litigation hold, we can use this:

Get-Mailbox -Filter {LitigationHoldEnabled -eq $true}

The corresponding parameter for In-Place holds however, InPlaceHolds, is multi-valued and I cannot find any way of making the filter work. I know I can filter it 'client-side', but this will not work. The whole idea is to create a filter for a custom management scope in order to create a new Role Group that will only have access to mailboxes that are put on hold.

Any ideas if this can be achieved and how?