Support JSON tags

[jaupe]

Is your feature request related to a problem? Please describe. The JSON we send back needs to be lower-case. We don't want to add it to the generated model structs because if we re-generate, then we will lose the tags.

Describe the solution you'd like Ability to add JSON tags in a maintenance-free manner if we re-generate the schema

[go-jet]

Hi @jaupe. It is possible to add tags to model types using generator customization. Check the test sample.