[Lync 2013] Response groups : description size

Hi.

I have difficulties to create or modify groups, queues or workflows with no descriptions.

In the web interface, I can set whatever I want as a description for these objects, including empty description, but when I try to do the same using the powershell commands, I have errors.

For example, I first create a queue with the following command :

New-CsRgsQueue -Name 'MyName' -Parent 'service:ApplicationServer:LYNC2013Finale.ciscoad.lab' -Description $Null

I then change the description with the following commands :

$KURMI_GETQUEUE = Get-CsRgsQueue -Identity 'service:ApplicationServer:LYNC2013Finale.ciscoad.lab/ba74e783-71b6-4952-ade7-4afbf2599653';
$KURMI_GETQUEUE.Description = 'MyDescription';
Set-CsRgsQueue -Instance $KURMI_GETQUEUE;

Once again, it works correctly, but if I try later to empty the description I have an error :

$KURMI_GETQUEUE = Get-CsRgsQueue -Identity 'service:ApplicationServer:LYNC2013Finale.ciscoad.lab/ba74e783-71b6-4952-ade7-4afbf2599653';
$KURMI_GETQUEUE.Description = $Null;
Set-CsRgsQueue -Instance $KURMI_GETQUEUE;

The error (SetValueInvocationException) tells me that the minimal length of description is 1.

Il also tried to use the '' value, but the error is the same.

How can I empty a description ?