Models: `minimum: null/maximum: null` for `string` and `boolean` seem redundant

[SerVB]

In the models section, there are redundant fields:

Current workaround is activating mapper.setSerializationInclusion(Include.NON_NULL) for Jackson.

However, it changes the way the server answers, so it's not a solution in some cases.

I think the solution can be just to omit generating minimum and maximum for string and boolean in the models section.

This is an issue extracted from #12.

[Wicpar]

made appropriate modifications in the rewoked-model branch.

implementation 'com.github.papsign:Ktor-OpenAPI-Generator:reworked-model-SNAPSHOT' and to remove null and empty fields:

                get("/openapi.json") {
                    call.respond(application.openAPIGen.api.build())
                }

It will be merged into master when it is determined as clean and maintainable.

[SerVB]

Yep, this works! A small concern here that .build() is executed every time the request is performed. Maybe it's better to use a lazy property to store the built schema.

[Wicpar]

It is possible, in principle, to create new routes during runtime, so the model can in principle change. This is up to the user.