elementInfo example

'#theme_wrappers',
    ];
    // Move this element into sub-element 'value'.     unset($element['value']);
    foreach (Element::properties($element) as $key) {
      if (!in_array($key, $keys_not_to_copy)) {
        $element['value'][$key] = $element[$key];
      }
    }

    $element['value']['#type'] = $element['#base_type'];
    $element['value'] += static::elementInfo()->getInfo($element['#base_type']);
    // Make sure the #default_value key is set, so we can use it below.     $element['value'] += ['#default_value' => ''];

    // Turn original element into a text format wrapper.     $element['#attached']['library'][] = 'filter/drupal.filter';

    // Setup child container for the text format widget.     $element['format'] = [
      '#type' => 'container',
      '#theme_wrappers' => [
        'container__text_format_filter_wrapper',
      ],