BPMN21 — Examples - DI - Lanes and Nested Lanes.bpmn example is not according to the specifications

Examples - DI - Lanes and Nested Lanes.bpmn example is not according to the specifications.
In xml:
<bpmn:lane name="Lane 2 - 2" id="Lane_Lane2_2">
<bpmn:flowNodeRef>Task_UserTask</bpmn:flowNodeRef>
<bpmn:flowNodeRef>DataObject_Document</bpmn:flowNodeRef>
</bpmn:lane>

DataObject_Document is a dataObjectReference (and that derives directly from flowElement) and not a flowNode. The documentation clearly states that flowNodeRef should be a reference to a flowNode and not to a flowElement (this has even changed from beta1 to beta2).