EntityViewsData::processViewsDataForLanguage

protected EntityViewsData::processViewsDataForLanguage($table, FieldDefinitionInterface $field_definition, array &$views_field, $field_column_name)

protected function processViewsDataForLanguage($table, FieldDefinitionInterface $field_definition, array &$views_field, $field_column_name) {
  // Apply special titles for the langcode field.
  if ($field_definition->getName() == $this->entityType->getKey('langcode')) {
    if ($table == $this->entityType->getDataTable() || $table == $this->entityType->getRevisionDataTable()) {
      $views_field['title'] = $this->t('Translation language');
    }
    if ($table == $this->entityType->getBaseTable() || $table == $this->entityType->getRevisionTable()) {
      $views_field['title'] = $this->t('Original language');
    }
  }
}