/// <summary>
        /// Fetches all password lists and returns a single password list asynchronously.
        /// </summary>
        /// <returns></returns>
        public async Task <PasswordList> BuildAsync()
        {
            var passwordList = new PasswordList();

            foreach (var source in this._passwordListSources)
            {
                passwordList.AddRange(await source.FetchAsync());
            }

            return(passwordList);
        }