public static IDocumentationProviderEx GetDocumentationProviderEx(this ServicesContainer container) { var result = container.GetDocumentationProvider() as IDocumentationProviderEx; if (result == null) { var msg = string.Format("{0} is not registered as {1} service provider.", typeof(WebApiHtmlDocumentationProvider), typeof(IDocumentationProvider)); throw new InvalidOperationException(msg); } return(result); }