Bug 303831 Warnings logged when trying to merge changes to an MPart's 'closeable' attribute
Warnings are printed out to syserr. --- WARNING: Unknown feature found, reconciliation may fail: Part#closeable
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/workbench/ui/internal/XMLModelReconciler.java
private final Object before;
		Position(Object object, Object after, Object before) {
			this.object = object;
			this.after = after;
			this.before = before;
		}
		public Object getObject() {
			return object;
		}
		public Object getBefore() {
			return before;
		}
		public Object getAfter() {
			return after;
		}
	}
	private ModelDelta createMultiReferenceDelta(Collection<ModelDelta> deltas,
			List<Object> references, EObject eObject, EStructuralFeature feature, Element node) {
		NodeList referencedIds = (NodeList) node;
		List<Object> originalReferences = new ArrayList<Object>();
		List<Object> userReferences = new ArrayList<Object>();
		List<?> currentReferences = (List<?>) eObject.eGet(feature);
		for (int i = 0; i < referencedIds.getLength(); i++) {
			Node item = referencedIds.item(i);
			if (item instanceof Element) {
				Element reference = (Element) item;
				if (isUnset(reference)) {
					userReferences.add(createObject(deltas, reference, references));
				} else {
					String referenceId = reference.getAttribute(APPLICATIONELEMENT_ID_ATTNAME);