/**
  * @TODO Find out why this is never being called.
  *
  * Validation for services for BasicToolbox.
  * @param array $element
  * @param FormStateInterface $form_state
  */
 public static function addThisDisplayElementServicesValidate($element, FormStateInterface $form_state)
 {
     $bad = FALSE;
     $services = trim($element['#value']);
     $services = str_replace(' ', '', $services);
     if (!preg_match('/^[a-z\\_\\,0-9]+$/', $services)) {
         $bad = TRUE;
     }
     // @todo Validate the service names against AddThis.com. Give a notice when there are bad names.
     // Return error.
     if ($bad) {
         $form_state->setErrorByName($element['name'], t('The declared services are incorrect or nonexistent.'));
     }
 }