Deletes expired items from the cache.
Drupal\Core\Cache\CacheBackendInterface::delete()
Drupal\Core\Cache\CacheBackendInterface::deleteMultiple()
Drupal\Core\Cache\CacheBackendInterface::deleteTags()
Drupal\Core\Cache\CacheBackendInterface::deleteAll()
Drupal\Core\Cache\CacheBackendInterface::deleteExpired()
public function deleteExpired();