class TextFormat

class TextFormat extends FormElementBase {
    
    /**
     * {@inheritdoc}
     */
    public function getSourceElement(LanguageInterface $source_language, $source_config) {
        // Instead of the formatted output show a disabled textarea. This allows for
        // easier side-by-side comparison, especially with formats with text
        // editors.
        return $this->getTranslationElement($source_language, $source_config, $source_config) + [
            '#value' => $source_config['value'],
            '#disabled' => TRUE,
            '#allow_focus' => TRUE,
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getTranslationElement(LanguageInterface $translation_language, $source_config, $translation_config) {
        return [
            '#type' => 'text_format',
            // Override the #default_value property from the parent class.
'#default_value' => $translation_config['value'],
            '#format' => $translation_config['format'],
            // @see \Drupal\config_translation\Element\FormElementBase::getTranslationElement()
'#allowed_formats' => [
                $source_config['format'],
            ],
        ] + parent::getTranslationElement($translation_language, $source_config, $translation_config);
    }

}