refactor: introduce DiscriminatorUtils to separate handling of discriminator discoverability

[Mattias-Sehlstedt]

I was working on extending the discriminator discoverability for useOneOfInterfaces in combination with enums, but I encountered that I had to duplicate my logic in several places. To make the delta of my later change smaller and more clear, I have created a PR first where I remove this duplicated logic.

Since the discriminator is a complex concept that sometimes require very specific parsing, I have also elected to move this logic into a separate DiscriminatorUtils class. This is similar to the ExamplesUtils class that already exists.

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Summary by cubic

Centralized discriminator discovery and construction in DiscriminatorUtils, with DefaultCodegen delegating lookups and type/schema resolution. This removes duplicated logic, unifies oneOf/anyOf handling, and keeps behavior unchanged while preparing enum-based discriminators with useOneOfInterfaces.

• Refactors
  • Added org.openapitools.codegen.utils.DiscriminatorUtils with recursiveGetDiscriminator, getDiscriminatorSchema, getDiscriminatorPropertyType, and a shared helper for oneOf/anyOf alternatives with a single conflicting-name warning.
  • Replaced inlined logic in org.openapitools.codegen.DefaultCodegen with calls to DiscriminatorUtils; minor comment/wording fixes (e.g., “innermost”); no functional changes.

^{Written for commit 52d65ec. Summary will update on new commits.}

[cubic-dev-ai]

2 issues found across 2 files

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