rest/access_log_apache.go
func (u *accessLogUtil) ResponseTime() *time.Duration {
	if u.R.Env["ELAPSED_TIME"] != nil {
		return u.R.Env["ELAPSED_TIME"].(*time.Duration)
	}
	return nil
}
func (u *accessLogUtil) ResponseTime() *time.Duration {
	if u.R.Env["ELAPSED_TIME"] != nil {
		return u.R.Env["ELAPSED_TIME"].(*time.Duration)
	}
	return nil
}
// As mesured by the timer middleware.