Check if an entity can be deleted

Can we check and see if the entity should be deleted please?

Say you have an Event entity and you want to prevent them from being deleted if there are already sessions scheduled or something. I propose we add a canBeDeleted() method. Our placeholder method would just return TRUE, but entities could override it with something like

  /**
   * {@inheritdoc}
   */
  public function canBeDeleted() {
    $messenger = \Drupal::messenger();

    if (!empty($this->getSessions())) {
      $messenger->addMessage('I\'m sorry. I can\'t delete events which already have sessions.', 'error');
      return FALSE;
    }

    return TRUE;
  }