src/app/dbtext/storage/DbtextCollectionManager.php
private function readCachedGroupData(string $namespace) {
		// Due to confusion, no cached items are returned during development
		if (N2N::isDevelopmentModeOn()) return null;

		$groupData = null;
		try {
			$cacheItem = $this->cacheStore->get(self::APP_CACHE_PREFIX . $namespace, array());
			if ($cacheItem === null) return null;

			if ($cacheItem->data instanceof GroupData) {
				return $cacheItem->data;
			}
		} catch (CorruptedCacheStoreException $e) {
		}

		$this->clearCache($namespace);
		return null;
	}
private function readCachedGroupData(string $namespace) {
		// Due to confusion, no cached items are returned during development
		if (N2N::isDevelopmentModeOn()) return null;

		$groupData = null;
		try {
			$cacheItem = $this->cacheStore->get(self::APP_CACHE_PREFIX . $namespace, array());
			if ($cacheItem === null) return null;

			if ($cacheItem->data instanceof GroupData) {
				return $cacheItem->data;
			}
		} catch (CorruptedCacheStoreException $e) {
		}

		$this->clearCache($namespace);
		return null;
	}
Finds cached {@see GroupData} by given namespace.
If dbtext cache of namespace is corrupt it is cleared.

@param string $namespace
@return GroupData|mixed|null