You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: jwt.go
    path of file: ./repos/mayfly-go/server/pkg/config
    
    the code of the file until where you have to start completion: package config

import (
	"mayfly-go/pkg/log
    
func (j *Jwt) Default() {
	if j.Key == "" {
		// 如果配置文件中的jwt key为空，则随机生成字符串
		j.Key = stringx.Rand(32)
		logx.Warnf("未配置jwt.key, 随机生成key为: %s", j.Key)
	}

	if j.ExpireTime == 0 {
		j.ExpireTime = 1440
		logx.Warnf("未配置jwt.expire-time, 默认值: %d", j.ExpireTime)
	}
}