Classes/Console/Service/CacheService.php
public function flushByTags(array $tags, $group = null)
    {
        foreach ($tags as $tag) {
            if ($group === null) {
                $this->cacheManager->flushCachesByTag($tag);
            } else {
                $this->cacheManager->flushCachesInGroupByTag($group, $tag);
            }
        }
    }
public function flushByTags(array $tags, $group = null)
    {
        foreach ($tags as $tag) {
            if ($group === null) {
                $this->cacheManager->flushCachesByTag($tag);
            } else {
                $this->cacheManager->flushCachesInGroupByTag($group, $tag);
            }
        }
    }
Flushes caches by given tags, optionally only in a specified (single) group.

@param array $tags
@param string $group