package main

import (
	"fmt"
	"net/http"
)

func main() {
	http.HandleFunc("/x", func(w http.ResponseWriter, r *http.Request) { fmt.Fprintln(w, "/x") })
	http.HandleFunc("/x/", func(w http.ResponseWriter, r *http.Request) { fmt.Fprintln(w, "/x/") })
	http.ListenAndServe(":8080", nil)
}

正确：

错误：

看起来经过一层反代后，trailing slash被丢掉了