Using Kernel#Array changed xml request. When an id is nil the array is empty. That casued a different error to be thrown from the server. Instead of switching the tests to the new error the nil is caught up front.
…item_id_container! so it can be reused for most container elements that have ItemId
instance methods only take the variable data, it is more clean than passing in the node and options hash to every method, we'll see if the idea holds up once more of the service is implemented