How to revert the state when lookup canceled?

I implemented a code chooser use `com.intellij.codeInsight.lookup.Lookup`:

public class ReplaceAction extends EditorAction {

    public ReplaceAction() { super(new Handler()); }

    @Override
    public void update(Editor editor, Presentation presentation, DataContext dataContext) {
        super.update(editor, presentation, dataContext);
    }

    private static class Handler extends EditorActionHandler {
        @Override
        public void doExecute(final Editor editor, @Nullable Caret caret, DataContext dataContext) {
            if (!editor.getSelectionModel().hasSelection(true) || editor.getProject() == null) {
                return;
            }

            LookupElement[] items = new LookupElement[10];
            for (int i = 0; i < items.length; i++) {
                items[i] = LookupElementBuilder.create("lookup item " + i);
            }

            final LookupEx lookup = LookupManager.getInstance(editor.getProject()).showLookup(editor, items);
            if (lookup != null) {
                lookup.addLookupListener(new LookupAdapter() {
                    @Override
                    public void lookupCanceled(LookupEvent event) {
                        // TODO Reverts to the state before modification.
                    }
                });
            }
        }

        @Override
        protected boolean isEnabledForCaret(@NotNull Editor editor, @NotNull Caret caret, DataContext dataContext) {
            return editor.getSelectionModel().hasSelection(true);
        }
    }
}

How to revert the state in the `lookupCanceled(LookupEvent )` method?