fix: add mapBlankStringToNull option to JsonNullableModule

[krangerich]

Blank strings for non-String fields were silently deserialized as undefined() instead of of(null), breaking PATCH semantics. Default remains false for backwards compatibility.

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Summary by cubic

Adds a module option to control how blank strings deserialize for non-String JsonNullable fields. When enabled, "" or " " become JsonNullable.of(null) instead of undefined, restoring correct PATCH semantics. Default stays false for backward compatibility.

• New Features

  • JsonNullableModule.mapBlankStringToNull(boolean): if true, blank strings for non-String targets deserialize as JsonNullable.of(null). Strings are unaffected.
  • Configuration is passed through JsonNullableDeserializers and JsonNullableDeserializer; tests added.

• Migration

  • To enable: register new JsonNullableModule().mapBlankStringToNull(true).

^{Written for commit 67a328e. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 6 files