NEW: Application#SubdomainRedirect. Example: https://github.com/kataras/iris/blob/master/_examples/subdomains/redirect/main.go

Former-commit-id: d8dd7c426dc9f14c870f103fef703595a2915612

core/router/router.go

@@ -114,13 +114,13 @@ type WrapperFunc func(w http.ResponseWriter, r *http.Request, firstNextIsTheRout
 //
 // Before build.
 func (router *Router) WrapRouter(wrapperFunc WrapperFunc) {
-	router.mu.Lock()
-	defer router.mu.Unlock()
-
 	if wrapperFunc == nil {
 		return
 	}
 
+	router.mu.Lock()
+	defer router.mu.Unlock()
+
 	if router.wrapperFunc != nil {
 		// wrap into one function, from bottom to top, end to begin.
 		nextWrapper := wrapperFunc