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
if (oldMenu == reference) {
									return key;
								} else if (oldMenu == null
										&& ((MWindow) key).getMainMenu() == reference) {
									menuSet = true;
								}
								menuChanged = true;
								break;
							}
						}
					}
				}
				if (menuChanged && menuSet) {
					return null;
				} else if (appendedMenu && !menuSet && !menuChanged) {
					return null;
				}
			}
			if (reference instanceof MToolBar) {
				for (Entry<EObject, EList<FeatureChange>> entry : objectChanges.entrySet()) {
					EObject key = entry.getKey();
					if (key instanceof MPart) {
						for (FeatureChange change : entry.getValue()) {
							if (change.getFeatureName().equals(PART_TOOLBAR_ATTNAME)) {
								if (change.getValue() == reference) {
									return key;
								}
							}
						}
					}