/// <summary>
        /// If you want to add your own namespaces.
        /// Use RegistNamespace of OpdsNamespaces.
        /// Because this method is called from constructor,
        /// it should not be a virtual method.
        /// </summary>
        private static T InitializeNamespaces <T>(T feed)
            where T : SyndicationFeed
        {
            foreach (var @namespace in OpdsNamespaces.GetAll())
            {
                feed.AttributeExtensions[@namespace.Key] = @namespace.Value;
            }

            return(feed);
        }
        /// <summary>
        /// If you want to add your own namespaces.
        /// Use RegistNamespace of OpdsNamespaces.
        /// Because this method is called from constructor,
        /// it should not be a virtual method.
        /// </summary>
        private static T InitializeNamespaces <T>(T item)
            where T : SyndicationItem
        {
            foreach (var @namespace in OpdsNamespaces.GetAll())
            {
                item.AttributeExtensions[@namespace.Key] = @namespace.Value;
            }

            return(item);
        }
        public void GetAllOpdsNamespacesTest()
        {
            var namespaces = OpdsNamespaces.GetAll();

            foreach (var ns in namespaces)
            {
                Assert.IsNotNull(ns);
                Assert.IsNotNull(ns.Value);
                Assert.IsNotNull(ns.Key);
                Assert.IsNotNull(ns.Key.Name);
            }
        }