The hack for substitution of standard configuration file

AppConfigChanger.cs

/// <summary>
    /// The hack for substitution of standard configuration file
    /// question at StackOweflow: http://stackoverflow.com/questions/6150644/change-default-app-config-at-runtime
    /// a solution: http://stackoverflow.com/a/6151688/2833774
    /// </summary>
    public abstract class AppConfigChanger : IDisposable
    {
        public static AppConfigChanger Change(string path)
        {
            return new AppConfigSubstitutor(path);
        }

        public abstract void Dispose();

        private class AppConfigSubstitutor : AppConfigChanger
        {
            private readonly string _oldConfig = AppDomain.CurrentDomain.GetData("APP_CONFIG_FILE").ToString();

            private bool _disposedValue;

            public AppConfigSubstitutor(string path)
            {
                AppDomain.CurrentDomain.SetData("APP_CONFIG_FILE", path);
                ResetConfigMechanism();
            }

            public override void Dispose()
            {
                if (!_disposedValue)
                {
                    AppDomain.CurrentDomain.SetData("APP_CONFIG_FILE", _oldConfig);
                    ResetConfigMechanism();

                    _disposedValue = true;
                }
                GC.SuppressFinalize(this);
            }

            private static void ResetConfigMechanism()
            {
                var initState = typeof(ConfigurationManager).GetField("s_initState", BindingFlags.NonPublic | BindingFlags.Static);
                if (initState == null) return;
                initState.SetValue(null, 0);

                var configSystem = typeof(ConfigurationManager).GetField("s_configSystem", BindingFlags.NonPublic | BindingFlags.Static);
                if (configSystem == null) return;
                configSystem.SetValue(null, null);

                var clientConfigPaths = typeof(ConfigurationManager).Assembly.GetTypes().Where(x => x.FullName == "System.Configuration.ClientConfigPaths");
                var clientConfigPath = clientConfigPaths.First().GetField("s_current", BindingFlags.NonPublic | BindingFlags.Static);
                if (clientConfigPath == null) return;
                clientConfigPath.SetValue(null, null);
            }
        }
    }