Example generation: nullable fields not visible in types

[ccudennec-otto]

Describe the bug
The schema generation currently does not properly support nullable types.

Example:

class Person {
  @Schema(nullable = true)
  private String name;
}

IMHO this should generate the following specification in asyncapi:

    Person
      title: Person
      type: object
      properties:
        name:
          types: [ "string", "null" ]

Compare the documentation of "null" types in the AsyncAPI + JSON schema specification:

• https://www.asyncapi.com/docs/reference/specification/v3.0.0#schemaObject
• https://json-schema.org/draft-07/schema

Dependencies and versions used

• springwolf-kafka version 1.17.0
• springwolf-ui version 1.X.0

Checklist for follow-up tasks discovered during implementation:

• Maintainer note: Use OpenAPI 3.1 fields (deprecate OpenAPI 3.0 fields) -> moved to Use OpenAPI 3.1 fields #1487
• Migrate to AssertJ (i.e. using openRewrite) -> feat(core): Support for nullable types #1416 (comment)

[github-actions]

The change is staged for release and will be part of the next release.

If you want to try and verify it in your application today,
use the latest 1.X.0-SNAPSHOT build as described in our README.md > Testing SNAPSHOT version

Thank you for the report/contribution!

[github-actions]

The change is available in the latest release (v1.19.0). 🎉

Thank you for the report/contribution and making Springwolf better!