FieldConfigDeleteForm::buildForm

public FieldConfigDeleteForm::buildForm(array $form, FormStateInterface $form_state)

public function buildForm(array $form, FormStateInterface $form_state) {
  $form = parent::buildForm($form, $form_state);

  // If we are adding the field storage as a dependency to delete, then that
  // will list the field as a dependency. That is confusing, so remove it.
  // Also remove the entity type and the whole entity deletions details
  // element if nothing else is in there.
  if (isset($form['entity_deletes']['field_config']['#items']) && isset($form['entity_deletes']['field_config']['#items'][$this->entity->id()])) {
    unset($form['entity_deletes']['field_config']['#items'][$this->entity->id()]);
    if (empty($form['entity_deletes']['field_config']['#items'])) {
      unset($form['entity_deletes']['field_config']);
      if (!Element::children($form['entity_deletes'])) {
        $form['entity_deletes']['#access'] = FALSE;
      }
    }
  }
  return $form;
}