ProfileTranslationHandler::entityFormSave

public ProfileTranslationHandler::entityFormSave(array $form, FormStateInterface $form_state)

public function entityFormSave(array $form, FormStateInterface $form_state) {
  if ($this->getSourceLangcode($form_state)) {
    $entity = $form_state->getFormObject()->getEntity();
    // We need a redirect here, otherwise we would get an access denied page
    // since the current URL would be preserved and we would try to add a
    // translation for a language that already has a translation.
    $form_state->setRedirectUrl($entity->urlInfo());
  }
}