feat(spring): add x-inner-validation vendor extension for collection items

[adraarda23]

Introduces a new field-level OpenAPI vendor extension x-inner-validation that places a custom annotation on the type argument of Java collections (List, Set) generated by the Spring server generator, enabling per-element bean validation constraints such as @NotNull. When set on the items schema, the generated POJO field, getter, setter and fluent builder all use the annotated parameterized type, e.g.:

private List<@jakarta.validation.constraints.NotNull Stubb> sample;

The implementation precomputes the full datatype string in SpringCodegen#postProcessModelProperty and exposes it via x-datatype-with-inner-annotation on the property; a small mustache partial (dataTypeWithInnerAnnotation) then renders that string or falls back to {{datatypeWithEnum}}, so existing models without the extension produce byte-identical output. The wrap is also propagated through JsonNullable<...> for nullable containers. Map / additionalProperties is intentionally not covered by this extension.

Scoped to the Spring generator on purpose: the issue author's reference attempt was on JavaSpring/pojo.mustache and Spring has no library overrides for that template, so coverage is complete here. Other Java and JaxRS generators have library-specific pojo overrides that would each need to be wired up separately; that can be added in a follow-up if requested.

Fixes #23705

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Summary by cubic

Adds x-inner-validation to the Spring generator to place type-use annotations on collection element types (e.g., List<@jakarta.validation.constraints.NotNull Foo>), enabling per-element bean validation. Docs now clarify the extension is set on the array/set items schema; fixes #23705.

• New Features
  • Set x-inner-validation on array items to inject an annotation on List/Set element types; uses Set when uniqueItems: true.
  • Propagates to fields, getters, setters, fluent setters, and through JsonNullable<...>.
  • No change when absent; scoped to Spring only; not applied to Map/additionalProperties.

^{Written for commit 474c60c. Summary will update on new commits.}

[cubic-dev-ai]

1 issue found across 10 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="docs/generators/spring.md">

<violation number="1" location="docs/generators/spring.md:147">
P2: The docs say `x-inner-validation` is a FIELD extension, but Spring only reads it from array/set `items`, so the placement is misleading.</violation>
</file>

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