[REQ] Generate a Class Diagram for complex Schemas

Created by: pburls

Is your feature request related to a problem? Please describe.

I work on a project with a large, rich data model exposed over several interfaces and I am busy trying to create OpenAPI specifications for these existing interfaces for the first time.

I've taken the opportunity to introduce some additional abstractions and data types to really leverage inheritance and composition to reduce repetition of properties without changing the actual structure of the final messages.

To help everyone involved understand these abstractions I've added, I would really like to be able to generate some kind of Class/Entity Diagram to show all the attributes and relationships from all the schemas in the OpenAPI spec files I have created. It will also be useful to add to the documentation for the interfaces going forward.

Describe the solution you'd like

I would really like to be able to generate a PlantUML Class or Entity diagram from the schames in a given OpenAPI file.

Describe alternatives you've considered

I have thought about generating the model code for a language as already supported and then using an appropriate class diagram generating tool using the code. It does seem like a bit of a round about approach and requires the language to support multiple inheritance. This doesn't seem ideal.