/// <summary>
        /// Registers the extension.
        /// </summary>
        /// <param name="extension">The extension.</param>
        public void RegisterExtension(IAnkhRevisionProvider extension)
        {
            if (extension == null)
                throw new ArgumentNullException("extension");

            _providers.Add(extension);
        }
        /// <summary>
        /// Registers the extension.
        /// </summary>
        /// <param name="extension">The extension.</param>
        public void RegisterExtension(IAnkhRevisionProvider extension)
        {
            if (extension == null)
            {
                throw new ArgumentNullException("extension");
            }

            _providers.Add(extension);
        }