Allow for custom struct tags such as json.

[naquin]

This is useful when using structs from 3rd-party packages which almost certainly only have json tags and not yaml tags.

This implementation does not change the default behavior for only looking for yaml tags, but allows the user to specify a list of tags to consider such as []string{"yaml", "json"} in an encoder or decoder.

[dolmen]

The default naming for keys which have no struct tags at all is different between gopkg.in/yaml.v3 and encoding/json: encoding/json use lower case while yaml.v3 keeps the original case. Here is an example: https://go.dev/play/p/L-oDNQ3nd9G

So I think that handling json struct tag will be the universal solution that you expect. It will only bring different breaking changes in serialization and more headaches for developers.