public function getLocationOptions() {
    static $options = [];

    if (!$options) {
      $options = [
        'All' => $this->t('All'),
        'branches' => [],
        'camps' => [],
      ];
      $map = [
        'branch' => 'branches',
        'camp' => 'camps',
      ];
      $query = $this->entityQuery
        ->get('node')
        ->condition('status', 1)
        ->condition('type', ['branch', 'camp'], 'IN');
      $entity_ids = $query->execute();
      $nodes = $this->entityTypeManager->getStorage('node')
        ->loadMultiple($entity_ids);
      foreach ($nodes as $id => $node) {
        $options[$map[$node->bundle()]][$id] = $node->getTitle();
      }
      // Remove empty option categories.
      foreach ($options as $key => $option) {
        if (empty($option)) {
          unset($options[$key]);
        }
      }
    }

    return $options;
  }