+ def empty_collection_uuid
+ 'd41d8cd98f00b204e9800998ecf8427e+0'
+ end
+
+ def empty_collection
+ if not $empty_collection
+ act_as_system_user do
+ ActiveRecord::Base.transaction do
+ $empty_collection = Collection.
+ where(portable_data_hash: empty_collection_uuid).
+ first_or_create!(manifest_text: '', owner_uuid: anonymous_group.uuid)
+ end
+ end
+ end
+ $empty_collection
+ end