/// <summary>
        /// Call this method to add a <see cref="IDbDependencyResolver" /> instance to the Chain of Responsibility
        /// of resolvers that are used to resolve dependencies needed by the Entity Framework. Unlike the AddDependencyResolver
        /// method, this method puts the resolver at the bottom of the Chain of Responsibility such that it will only
        /// be used to resolve a dependency that could not be resolved by any of the other resolvers.
        /// </summary>
        /// <param name="resolver"> The resolver to add. </param>
        public void AddDefaultResolver(IDbDependencyResolver resolver)
        {
            Check.NotNull(resolver, "resolver");

            _internalConfiguration.CheckNotLocked("AddDefaultResolver");
            _internalConfiguration.AddDefaultResolver(resolver);
        }
        private void RegisterDbProviderServices()
        {
            var providers = _appConfig.DbProviderServices;

            if (providers.All(p => p.InvariantName != "System.Data.SqlClient"))
            {
                // If no SQL Server provider is registered, then make sure the SQL Server provider is available
                // by convention (if it can be loaded) as it would have been in previous versions of EF.
                RegisterSqlServerProvider();
            }

            providers.Each(
                p =>
            {
                _providerFactories[p.InvariantName] = p.ProviderServices;
                _internalConfiguration.AddDefaultResolver(p.ProviderServices);
            });
        }