/** * {@inheritdoc} */ public function validateForm(array &$form, FormStateInterface $form_state) { if (isset($form_state->getTriggeringElement()['#delta'])) { $delta = $form_state->getTriggeringElement()['#delta']; $this->feedType->getTargetPlugin($delta)->validateConfigurationForm($form, $form_state); $form_state->setRebuild(); } }