coanor

For my case, it's simple to add customize header in response: ```golang router := gin.New() router.Use(func(c *gin.Context) { c.Header("X-Your-Header-Name", "your-header-value") }) // some other middleware... // add router router.GET("/some/api", apiHandler)...

My use case is to setup some Prometheuse metrics on log rotate, this may usefull to count how many files(bytes, approximately) been logged.