Can't load config into struct with json tags about confita HOT 1 OPEN

package main

import (
	"context"
	"github.com/heetch/confita"
	"github.com/heetch/confita/backend/file"
	"github.com/heetch/confita/backend/flags"
	log "github.com/sirupsen/logrus"
	"time"
)

type Config struct {
	Host        string        `config:"host"`
	Port        uint32        `config:"port"`
	Timeout     time.Duration `config:"timeout"`
	Password    string        `config:"password"`
	Name string `config:"name,required"`
	OrderValue float64 `config:"order_value"`
	itemNumber int `config:"item_number"`
}

func main() {
	loader := confita.NewLoader(
		file.NewBackend("cmd/confita/config.json"),
		flags.NewBackend(),
		)

	// default values
	cfg := Config{
		Host: "127.0.0.1",
		Port: 5656,
		Timeout: 5 * time.Second,
	}

	ctx, cancel := context.WithTimeout(context.Background(), 5 * time.Second)
	defer cancel()

	// loading configuration
	if err := loader.Load(ctx, &cfg); err != nil {
		log.WithError(err).Fatal("loading config")
	}


	// check the config
	log.WithField("config", cfg).Info("config loaded")
}