[FEATURE] Ensure Java / Kotlin code is marked as generated

[michael-schechter-simspace]

Why do we need this improvement?

This improvement is needed so that generated code can easily be excluded from quality analysis by standard JVM tooling.

How will this change help?

Some quality tools allow exclusion by filesystem path or package; others require annotations to exclude the code. This change will improve ease of use for JVM-based consumers.

Screenshots

No response

How could it be implemented/designed?

Any generated class must be annotated with jakarta.annotation.Generated to simplify excluding the code from various quality tools.

🚧 Breaking changes

No

👀 Have you checked for similar open issues?

• I checked and didn't find a similar issue

🏢 Have you read the Contributing Guidelines?

• I have read the Contributing Guidelines

Are you willing to work on this issue?

No, someone else can work on it.

[GishReloaded]

Hi! I'd like to work on this if it is available.

I traced asyncapi generate models and it delegates Java/Kotlin rendering to @asyncapi/modelina-cli, so the main implementation appears to belong in asyncapi/modelina, with the CLI consuming the updated Modelina version/options.

My proposed approach:

1. Add generated-code annotation support to the Java and Kotlin class/enum renderers using the existing preset and dependency-manager patterns.
2. Emit the appropriate jakarta.annotation.Generated import and annotation without affecting other languages.
3. Add generator tests/snapshots for Java and Kotlin output.
4. Verify whether CLI option/version wiring is needed and add an integration test if applicable.

Could a maintainer confirm whether the implementation should be opened in asyncapi/modelina and whether all generated model types (classes, enums, records/unions) are expected to be annotated?