VirtualFileEnumeration () { IntSet result = new IntOpenHashSet(); for (VirtualFile file : myRoots.keySet()) { if (file instanceof VirtualFileWithId) { int[] children = VirtualFileManager.getInstance().listAllChildIds(((VirtualFileWithId)file).getId()); result.addAll(IntList.of(children)); } } return new MyVirtualFileEnumeration(result); }