private function traverse() {
    if (!$result = $this->queryFactory->get(GroupexFormCacheManager::ENTITY_TYPE)->execute()) {
      return;
    }

    // Loop over each cache entity.
    $this->logger->info('Starting warming up %count cache entities.', ['%count' => count($result)]);
    krsort($result);
    foreach ($result as $item) {
      // Let's protect GroupEx servers.
      sleep(1);

      if (!$entity = GroupexFormCache::load($item)) {
        continue;
      }

      if (!$this->needsWarmUp($entity)) {
        continue;
      }

      $this->warmUp($entity);
    }
  }