class ListElement

class ListElement implements ElementInterface {
    use StringTranslationTrait;
    
    /**
     * The schema element this form is for.
     *
     * @var \Drupal\Core\TypedData\TraversableTypedDataInterface
     */
    protected $element;
    
    /**
     * Constructs a ListElement.
     *
     * @param \Drupal\Core\TypedData\TraversableTypedDataInterface $element
     *   The schema element this form element is for.
     */
    public function __construct(TraversableTypedDataInterface $element) {
        $this->element = $element;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(TypedDataInterface $schema) {
        return new static($schema);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getTranslationBuild(LanguageInterface $source_language, LanguageInterface $translation_language, $source_config, $translation_config, array $parents, $base_key = NULL) {
        $build = [];
        foreach ($this->element as $key => $element) {
            $sub_build = [];
            $element_key = isset($base_key) ? "{$base_key}.{$key}" : $key;
            $definition = $element->getDataDefinition();
            if ($form_element = ConfigTranslationFormBase::createFormElement($element)) {
                $element_parents = array_merge($parents, [
                    $key,
                ]);
                $sub_build += $form_element->getTranslationBuild($source_language, $translation_language, $source_config[$key], $translation_config[$key], $element_parents, $element_key);
                if (empty($sub_build)) {
                    continue;
                }
                // Build the sub-structure and include it with a wrapper in the form if
                // there are any translatable elements there.
                $build[$key] = [];
                if ($element instanceof TraversableTypedDataInterface) {
                    $build[$key] = [
                        '#type' => 'details',
                        '#title' => $this->getGroupTitle($definition, $sub_build),
                        '#open' => empty($base_key),
                    ];
                }
                $build[$key] += $sub_build;
            }
        }
        return $build;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setConfig(Config $base_config, LanguageConfigOverride $config_translation, $config_values, $base_key = NULL) {
        foreach ($this->element as $key => $element) {
            $element_key = isset($base_key) ? "{$base_key}.{$key}" : $key;
            if ($form_element = ConfigTranslationFormBase::createFormElement($element)) {
                // Traverse into the next level of the configuration.
                $value = $config_values[$key] ?? NULL;
                $form_element->setConfig($base_config, $config_translation, $value, $element_key);
            }
        }
    }
    
    /**
     * Returns the title for the 'details' element of a group of schema elements.
     *
     * For some configuration elements the same element structure can be repeated
     * multiple times (for example views displays, filters, etc.). Thus, we try to
     * find a more usable title for the details summary. First check if there is
     * an element which is called title or label and use its value. Then check if
     * there is an element which contains these words and use those. Fall back
     * to the generic definition label if no such element is found.
     *
     * @param \Drupal\Core\TypedData\DataDefinitionInterface $definition
     *   The definition of the schema element.
     * @param array $group_build
     *   The renderable array for the group of schema elements.
     *
     * @return string
     *   The title for the group of schema elements.
     */
    protected function getGroupTitle(DataDefinitionInterface $definition, array $group_build) {
        $title = '';
        if (isset($group_build['title']['source'])) {
            $title = $group_build['title']['source']['#markup'];
        }
        elseif (isset($group_build['label']['source'])) {
            $title = $group_build['label']['source']['#markup'];
        }
        else {
            foreach (array_keys($group_build) as $title_key) {
                if (isset($group_build[$title_key]['source']) && (str_contains($title_key, 'title') || str_contains($title_key, 'label'))) {
                    $title = $group_build[$title_key]['source']['#markup'];
                    break;
                }
            }
        }
        return (!empty($title) ? strip_tags($title) . ' ' : '') . $this->t($definition['label']);
    }

}