tonic: Refactor handling of comma-separated lists
I think we have to review the following, because it uses the current ExplodeTag. https://github.com/loopfz/gadgeto/blob/66ad4638c25c77275b47b89dd23d013c36aaae48/tonic/handler.go#L211
The code seems also useless. I don't think we need to take the ExplodeTag into account for default values. We could simply state that multiple values can be defined in a default tag, by delimiting them with a comma, and split that to feed the fieldValues slice. Later on, if the actual type of the field is not array or slice, we'll catch it and return an error. https://github.com/loopfz/gadgeto/blob/66ad4638c25c77275b47b89dd23d013c36aaae48/tonic/handler.go#L236
That will allow a user to specify multiple default values for arrays and slices, but we can't do much without adding complexity to prevent a misuse.
Not closing this right now, but will need to reassess