Bug 317954 Version deltas file so that incompatible changes will be ignored
The deltas file needs to be versioned so that incompatible changes will be discarded allowing the workbench to be constructed as if there were no deltas in existence.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/XMLModelReconciler.java
deltas.add(delta);
				} else {
					ModelDelta delta = createAttributeDelta(object, feature, innerElement,
							featureName);
					deltas.add(delta);
				}
			}
		}
	}
	private ModelDelta createDirectReferenceDelta(Collection<ModelDelta> deltas,
			List<Object> references, EObject eObject, EStructuralFeature feature, Element node) {
		NodeList referencedIds = (NodeList) node;
		Element reference = getFirstElement(referencedIds);
		String referenceId = reference.getAttribute(APPLICATIONELEMENT_ELEMENTID_ATTNAME);
		Object match = findReference(references, referenceId);
		if (match == null) {
			
			match = createObject(deltas, reference, references);
		}
		return new EMFModelDeltaSet(eObject, feature, match);
	}
	private static Element getFirstElement(NodeList list) {
		for (int i = 0; i < list.getLength(); i++) {
			Node item = list.item(i);
			if (item instanceof Element) {
				return (Element) item;
			}
		}
		return null;
	}