/// <inheritdoc />
        public string GetAccessToken()
        {
            var tenantUrl    = Settings.GetSetting("Foundation.FotoWareExtensions.FotoWare.TenantUrl", string.Empty);
            var clientId     = Settings.GetSetting("Foundation.FotoWareExtensions.FotoWare.ClientId", string.Empty);
            var clientSecret = Settings.GetSetting("Foundation.FotoWareExtensions.FotoWare.ClientSecret", string.Empty);

            if (string.IsNullOrEmpty(tenantUrl) ||
                string.IsNullOrEmpty(clientId) ||
                string.IsNullOrEmpty(clientSecret))
            {
                FotoWareFieldsLog.WriteToLog("--- Authentication Service: FotoWare-Setings are incomplete or not exists ---");
                return(string.Empty);
            }

            return(_fotoWareRepository.GetAccessToken(tenantUrl, clientId, clientSecret));
        }