/**
* @inheritdoc
*/
public function submitOptionsForm(&$form, FormStateInterface $form_state)
{
// Merge plural format options into one string and drop the individual
// option values.
$options =& $form_state->getValue('options');
$options['format_plural_string'] = implode(LOCALE_PLURAL_DELIMITER, $options['format_plural_values']);
unset($options['format_plural_values']);
parent::submitOptionsForm($form, $form_state);
}