Page callback for the translation edit page.
\Drupal\Core\Entity\EntityInterface $entity: The entity being translated.
\Drupal\Core\Language\Language $language: (optional) The language of the translated values. Defaults to the current content language.
array A processed form array ready to be rendered.
function translation_entity_edit_page(EntityInterface $entity, Language $language = NULL) {
$language = !empty($language) ? $language : language(Language::TYPE_CONTENT);
$info = $entity
->entityInfo();
$operation = isset($info['default_operation']) ? $info['default_operation'] : 'default';
$form_state['langcode'] = $language->langcode;
$form_state['translation_entity']['translation_form'] = TRUE;
return entity_get_form($entity, $operation, $form_state);
}