/// <summary>
 /// Inner dispose
 /// </summary>
 /// <param name="disposing">disposing flag</param>
 protected virtual void Dispose(bool disposing)
 {
     if (disposing && _service != null)
     {
         _service.Dispose();
         _service = null;
     }
 }
        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="serviceUrl">Service URL</param>
        public PaymentSystemClient(string serviceUrl)
        {
            if (string.IsNullOrWhiteSpace(serviceUrl))
            {
                throw new ArgumentException("Value cannot be null or whitespace.", nameof(serviceUrl));
            }

            _service = new PaymentSystemAPI(new Uri(serviceUrl), new HttpClient());
        }