Empty description of a booking method is diplayed wrong occasionally

In some cases the discription of booking method is displayed as "$confController.getLink().getOffer().getDescription()", possibly if the description is not an empty String, but a null value.

The following code in accesscontrol/ui/_content/configuration_list.html fixes that
#set($desc = $confController.getLink().getOffer().getDescription())
#if ($desc)
<tr class="$css b_access_desc">
<td colspan="5">$desc</td>
</tr>
#end