Expanded class hierarchy of DateFieldWidgetBase in Date 8
- class \Drupal\date_field\Plugin\field\widget\DateFieldWidgetBase extends \Drupal\field\Plugin\Type\Widget\WidgetBase
- class \Drupal\date_field\Plugin\field\widget\DateFieldDatepickerWidget
- class \Drupal\date_field\Plugin\field\widget\DateFieldListWidget