Quick sketch of pulling together data required to build nested routes

gistfile1.cs

var timer = new Stopwatch();
timer.Start();

var configuration = GlobalConfiguration.Configuration;

var explorer = new ApiExplorer(configuration);
var descriptions = explorer.ApiDescriptions;

var controllerDescriptors = descriptions.Select(o => o.ActionDescriptor.ControllerDescriptor).Distinct().ToList();

var nestedController =
    controllerDescriptors.Where(o => typeof(INestedApiController).IsAssignableFrom(o.ControllerType))
                         .Select(
                             o =>
                             new
                                 {
                                     Descriptor = o,
                                     NestedUnder = FindRelatedControllerDescriptor(controllerDescriptors, o),
                                     NestedDescription = descriptions.Where(d => d.ActionDescriptor.ControllerDescriptor == FindRelatedControllerDescriptor(controllerDescriptors, o)).ToList(),
                                     ParentRoutes = descriptions.Where(d => d.ActionDescriptor.ControllerDescriptor == FindRelatedControllerDescriptor(controllerDescriptors, o)).Select(d => d.Route).Distinct().ToList(),
                                 }).First();

var routeName = nestedController.Descriptor.ControllerName + "-"
                + nestedController.NestedUnder.ControllerName;

var routes = nestedController.NestedUnder.Configuration.Routes;


/*----------------*/


private static HttpControllerDescriptor FindRelatedControllerDescriptor(IEnumerable<HttpControllerDescriptor> controllerDescriptors, HttpControllerDescriptor childDescriptor)
{
  return
      controllerDescriptors.FirstOrDefault(
          cd =>
          cd.ControllerType
          == childDescriptor.ControllerType.GetInterfaces()
              .First(i => i.GenericTypeArguments.Any())
              .GenericTypeArguments.FirstOrDefault());
}