proposal: encoding/json: ordered struct tag for maps

[dans-stuff]

Description

Add a struct tag for maps to sort by key while marshalling.

type MyStruct struct {
	Results map[string]int `json:",ordered"`
}

This would collect the keys of the map (which always resolve to strings), sort them using sort.Strings, and then encode each key/value in that order. This proposal is in response to seeing 2 instances of people asking how to encode a map with consistent ordering.

Edit: This would also help with unit testing.

Edit2: It seems this is already implemented without a struct tag - disregard.