* Traverses through all nodes to collect all affiliations of the user.
* @return the list of subscriptions or an empty list.
*/
private List<AffiliationItem> collectAffiliations(CollectionNode root, Entity sender) {
List<AffiliationItem> affiliations;
NodeAffiliationVisitor nodeAffiliationVisitor = new NodeAffiliationVisitor(sender);
root.acceptNodes(nodeAffiliationVisitor);
affiliations = nodeAffiliationVisitor.getAffiliations();
return affiliations;
}