log/filtered/filtered.go
func LowerCaseFilter(filter Filter) Filter {
	return FilterFunc(func(k string, v interface{}) interface{} {
		return filter.Filter(strings.ToLower(k), v)
	})
}
func LowerCaseFilter(filter Filter) Filter {
	return FilterFunc(func(k string, v interface{}) interface{} {
		return filter.Filter(strings.ToLower(k), v)
	})
}
// LowerCaseFilter creates a filter that only get passed lowercase field names