To optimize a custom widget's rebuilds, you can use the ______ method to maintain its state.

To optimize a custom widget's rebuilds, you can use the shouldRebuild() method to maintain its state. This method is part of the StatefulWidget lifecycle and is called during the rebuild process. By implementing the shouldRebuild() method, you can specify conditions under which the widget should rebuild or remain unchanged. This can significantly improve performance by preventing unnecessary rebuilds and updates, ensuring that your custom widget updates only when needed.