public IDocumentStorage CreateDocumentStorage()
        {
            if(_storage == null)
            {
                _storage = new CacheDocumentStorage(_concreteStorageFactory.CreateDocumentStorage());
            }

            return _storage;
        }
        public IDocumentStorage CreateDocumentStorage(ISession session, Configuration configuration)
        {
            if (_storage == null)
            {
                _storage = new CacheDocumentStorage(_concreteStorageFactory.CreateDocumentStorage(session, configuration));
            }

            return _storage;
        }