package main

import (
	"fmt"
	"testing"

	"github.com/goccy/go-json"
)

func main() {
	type Container struct {
		V any `json:"value"`
	}
	type MapOnly struct {
		Map map[string]int64 `json:"map"`
	}

	b, err := json.Marshal(Container{MapOnly{}})
	if err != nil {
		panic(err)
	}

	fmt.Println(string(b))
}