why gproperties.Decode() let lastKey to lower?

[yiqiang3344]

func Decode(data []byte) (res map[string]interface{}, err error) {
	res = make(map[string]interface{})
	pr, err := properties.Load(data, properties.UTF8)
	if err != nil || pr == nil {
		err = gerror.Wrapf(err, `Lib magiconair load Properties data failed.`)
		return nil, err
	}
	for _, key := range pr.Keys() {
		// ignore existence check: we know it's there
		value, _ := pr.Get(key)
		// recursively build nested maps
		path := strings.Split(key, ".")
		lastKey := strings.ToLower(path[len(path)-1])
		deepestMap := deepSearch(res, path[0:len(path)-1])

		// set innermost value
		deepestMap[lastKey] = value
	}
	return res, nil
}

this let gproperties type config can't get right value of camel-case key。