@Override public List<String> getInvalidRootUrls(OrderRootType type) { if (myDisposed) return Collections.emptyList(); final List<VirtualFilePointer> pointers = myRoots.get(type).getList(); List<String> invalidPaths = null; for (VirtualFilePointer pointer : pointers) { if (!pointer.isValid()) { if (invalidPaths == null) { invalidPaths = new SmartList<String>(); } invalidPaths.add(pointer.getUrl()); } } return invalidPaths == null ? Collections.<String>emptyList() : invalidPaths; }