ContentEntityForm::initFormLangcodes

protected ContentEntityForm::initFormLangcodes(FormStateInterface $form_state)

protected function initFormLangcodes(FormStateInterface $form_state) {
  // Store the entity default language to allow checking whether the form is
  // dealing with the original entity or a translation.
  if (!$form_state->has('entity_default_langcode')) {
    $form_state->set('entity_default_langcode', $this->entity->getUntranslated()->language()->getId());
  }
  // This value might have been explicitly populated to work with a particular
  // entity translation. If not we fall back to the most proper language based
  // on contextual information.
  if (!$form_state->has('langcode')) {
    // Imply a 'view' operation to ensure users edit entities in the same
    // language they are displayed. This allows to keep contextual editing
    // working also for multilingual entities.
    $form_state->set('langcode', $this->entityManager->getTranslationFromContext($this->entity)->language()->getId());
  }
}