PSR-6 Cache getItem/getItems bug

    /**
     * Returns a Cache Item representing the specified key.
     *
     * This method must always return a CacheItemInterface object, even in case of
     * a cache miss. It MUST NOT return null.
     *
     * @param string $key
     *   The key for which to return the corresponding Cache Item.
     *
     * @throws InvalidArgumentException
     *   If the $key string is not a legal value a \Psr\Cache\InvalidArgumentException
     *   MUST be thrown.
     *
     * @return CacheItemInterface
     *   The corresponding Cache Item.
     */
    public function getItem($key);

    /**
     * Returns a traversable set of cache items.
     *
     * @param string[] $keys
     *   An indexed array of keys of items to retrieve.
     *
     * @throws InvalidArgumentException
     *   If any of the keys in $keys are not a legal value a \Psr\Cache\InvalidArgumentException
     *   MUST be thrown.
     *
     * @return array|\Traversable
     *   A traversable collection of Cache Items keyed by the cache keys of
     *   each item. A Cache item will be returned for each key, even if that
     *   key is not found. However, if no keys are specified then an empty
     *   traversable MUST be returned instead.
     */
    public function getItems(array $keys = array());

Yii2Extended\Yii2Cache::getItem must always return CacheItemInterface

	public function getItem($key)
	{
		$value = $this->_yii2Cache->get($key);
		if(null === $value)
			$value = new Psr6ToYii2CacheItem($key);
		/** @psalm-suppress MixedReturnStatement */
		return $value; # <- return cached value instead, yii2 returns false when item not exists
	}

Yii2Extended\Yii2Cache::getItems must always return CacheItemInterface[] indexed by cache keys