Swagger-ui: Support Hierarchical Tags

[kael-shipman]

Is your feature request related to a problem?

There is growing support in the OAS community for the idea of hierarchical tags (see OAI/OpenAPI-Specification#1367). The current consensus is that UIs like SwaggerUI can implement this with no change required in the OAS, and that this would be a much appreciated feature. I would like to implement it in SwaggerUI and would like help identifying the best way to do so.

Describe the solution you'd like

Tags such as Petstore|Mammals|Dogs should render as

## Petstore

### Mammals

#### Dogs

....

[kael-shipman]

I'm willing and able to implement this, even if just for my own fork of SwaggerUI, so regardless of whether this feature gets official approval or not, I'd love for someone to give me a hint at where to start.

[MarcusBondezan]

This would be great! The doc would be much more organized for the front end folks of my project.

[kael-shipman]

Thanks for commenting! Good to know others find this desirable.

To the devs: I repeat my offer to implement this and PR it if you'll give me a push to start me in the right direction ;).

[effrafax]

Yes, would be great to have such a feature!

[SaiSrinivasM]

Yes, I am also looking for the same

[leandrofnunes]

It'd be awesome to have such feature available - as of now, I need to create composed tags which causes lots of duplicates.

[donaldduy-lb]

I would also love this feature!

[daveKoala]

I am also looking for the same thing.
My use case is, I have an existing API with 2 versions, about to start on the third, consumers add a field in the header asking for specified version. I think sub or hierarchical tags would make life so much easier for developers and readers of the docs. As i need to keep all versions in a single doc

Happy to be told that header accept version can be documented in a different manner

[mairead]

We need this feature too. Our API serves several products but also we have utility endpoints, global endpoints and product specific endpoints. It would be really helpful to be able to add sub headings and also even a description to each sub heading so you could explain the purpose of the grouping

[arkanmgerges]

Yes it is a good feature