fix(bug): Fix form validation does not work in Kotlin.

[Yue-plus]

Description

• -Xjsr305=strict: This argument changes how the Kotlin compiler handles nullability annotations. The strict mode means that the compiler will strictly check nullability annotations and give a warning or error when it finds a problem.
• -Xemit-jvm-type-annotations: This argument makes the Kotlin compiler emit JVM type annotations into the bytecode.

Fixes #2343

Type of change

• [x] Bugfix
• [ ] Feature

Checklist

• [x] I have read the contribution guide: https://vaadin.com/docs/latest/guide/contributing/overview/
• [x] I have added a description following the guideline.
• [x] The issue is created in the corresponding repository and I have referenced it.
• [x] I have added tests to ensure my change is effective and works as intended.
• [x] New and existing tests are passing locally with my change.
• [x] I have performed self-review and corrected misspellings.

Additional for Feature type of change

• [ ] Enhancement / new feature was discussed in a corresponding GitHub issue and Acceptance Criteria were created.

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[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[Yue-plus]

I apologize for my previous misunderstanding of the Groovy programming language. I was not aware that Groovy allows direct assignment to lists without the need to call the addAll method. I have tested these changes locally and confirmed their correctness. Please review this PR again, thank you.