feat: add support for complex default values in code generation

[jorgerod]

Closes: #24993

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[cubic-dev-ai]

All reported issues were addressed across 4 files

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[cubic-dev-ai]

All reported issues were addressed across 1 file (changes from recent commits).

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[cubic-dev-ai]

All reported issues were addressed across 474 files

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[Mattias-Sehlstedt]

I’d strongly recommend moving the default-construction logic into its own dedicated component rather than keeping it in AbstractJavaCodegen. That class already carries quite a bit of responsibility, so separating this into a more focused unit would likely make the design easier to manage, reason about, and extend/mimic. So similar to other Util components that have been introduced.

[cubic-dev-ai]

All reported issues were addressed across 26 files (changes from recent commits).

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[jorgerod]

@Mattias-Sehlstedt Thanks for the suggestion. I agreed that the complex default construction logic was becoming too large for AbstractJavaCodegen, so I extracted it into a focused JavaDefaultValueRenderer component in follow-up commit d8b7b798d77.

AbstractJavaCodegen now keeps the generator policy/configuration and delegates recursive default rendering through an explicit context containing schema resolution, Java naming/type conversion, collection construction, date-library configuration, and oneOf handling. This keeps the renderer reusable and makes the rendering logic easier to test without duplicating generator behavior.

The existing functional regressions remain covered, including arrays/objects, oneOf branch selection, date libraries, nullable defaults, and container initialization. The directed Java/Spring/Play tests pass and checkstyle passes.

[cubic-dev-ai]

All reported issues were addressed across 93 files

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[cubic-dev-ai]

All reported issues were addressed across 7 files (changes from recent commits).

<sub>Requires human review: Auto-approval blocked because this review re-detected 1 unresolved issue already reported by Cubic.
Tip: Review your code locally with the cubic CLI to iterate faster.

Re-trigger cubic</sub>

[cubic-dev-ai]

All reported issues were addressed across 1 file (changes from recent commits).

<sub>Tip: Review your code locally with the cubic CLI to iterate faster.

Re-trigger cubic</sub>