ImageToolkitForm::validateForm

public ImageToolkitForm::validateForm(array &$form, FormStateInterface $form_state)

public function validateForm(array &$form, FormStateInterface $form_state) {
  parent::validateForm($form, $form_state);

  // Call the form validation handler for each of the toolkits.
  foreach ($this->availableToolkits as $toolkit) {
    $toolkit->validateConfigurationForm($form, $form_state);
  }
}