code: private function checkboxCaption($key, $table, IAttribute $attribute)
      {
          return $this->translator->trans($table . '.' . $key, [$attribute->getName()], 'contao_' . $table);
      }
docs: Translate the checkbox caption.
  
  @param string     $key       The language sub key.
  @param string     $table     The table name.
  @param IAttribute $attribute The attribute.
  
  @return string