/// <summary>
        /// Dispose.
        /// </summary>
        /// <param name="disposing"></param>
        protected virtual void Dispose(Boolean disposing)
        {
            if (IsDisposed)
            {
                return;
            }
            IsDisposed = true;

            Underlying.Dispose();

            if (disposing)
            {
                // Dispose managed state (managed objects)
                Underlying?.Dispose();
            }
        }