/**
  * {@inheritdoc}
  */
 public function form(array $form, FormStateInterface $form_state)
 {
     $form = parent::form($form, $form_state);
     if ($this->getVariantPlugin() instanceof BlockVariantInterface) {
         $form['variant_settings']['block_section'] = $this->buildBlockForm();
     }
     $form['selection_section'] = $this->buildSelectionForm();
     return $form;
 }