5001: Add support for @Nullable annotations in OpenAPI 3.1 schemas

[zdary]

Pull Request

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Description

Enhanced schema generation by recognizing

• @nullable annotations as nullable and adding "null" to the type array in OpenAPI 3.1.
• nullable = true in schema and adding "null" to the type array in OpenAPI 3.1.

Introduced a test case to validate the behavior and ensure backward compatibility with explicit @Schema annotations.

Fixes: #5001 , #4555

Type of Change

• 🐛 Bug fix
• ✨ New feature
• ♻️ Refactor (non-breaking change)
• 🧪 Tests
• 📝 Documentation
• 🧹 Chore (build or tooling)

Checklist

• I have added/updated tests as needed
• I have added/updated documentation where applicable
• The PR title is descriptive
• The code builds and passes tests locally
• I have linked related issues (if any)

Screenshots / Additional Context

[ronodhirSoumik]

is this loop needed?

if (annotations != null) {
    return Arrays.stream(annotations).anyMatch(annotation ->
                NULLABLE_ANNOTATIONS.contains(annotation.annotationType().getSimpleName()));
 }

[zdary]

Yes, it is. Not sure how to write it more elegant than this. Feel free to correct it, please if you prefer

[ewaostrowska]

This version here removes redundancy. The loop variable ann was never used - it was just a mechanism to trigger the stream operation

[zdary]

@ronodhirSoumik will this PR make its way to the release? If so any eta?

[ewaostrowska]

@zdary thanks for providing PR for this issue. As @ronodhirSoumik was suggesting the loop and stream was not necessary effective there so I have introduced a small change. Otherwise this is great :) Solves as well #4555 which community especially seemed to waiting for. It will make it to the next release.