feat(jackson3): add jackson3 support for Java Client generator - WebClient

[phoval]

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Summary by cubic

Adds Jackson 3 support to the Java WebClient generator with Spring Boot 4, using Spring’s Jackson 3 codecs and Jakarta EE. Includes a new Petstore sample with Maven CI (Java 17/21) and adds it to the JDK17 samples workflow.

• New Features

  • New option: useJackson3 (requires useSpringBoot4; incompatible with openApiNullable).
  • Auto-enables Jakarta EE when useSpringBoot4 is true.
  • WebClient switches between Jackson 2 (ObjectMapper + Jackson2JsonEncoder/Decoder) and Jackson 3 (JsonMapper + JacksonJsonEncoder/Decoder); all Jackson imports (incl. XML) use jacksonPackage.
  • Dependencies: add jackson-core/databind from Jackson 3; keep com.fasterxml jackson-annotations with its own version; remove jackson-jaxrs-json-provider. Versions align with Spring Boot 4.0.3 (or 3.5.11 without Spring Boot 4), Jakarta Annotations 3.0.0, Swagger annotations 1.6.16/2.2.43. Non-Jackson3 samples use Jackson 2.21.1 with separate jackson-annotations.
  • New webclient-springBoot4-jackson3 config and Petstore sample; added to samples JDK17 workflow and sample Maven CI (Java 17/21).

• Bug Fixes

  • Restored FindBugs JSR 305 dependency to retain nullability annotations.

^{Written for commit 726f6c6. Summary will update on new commits.}

[cubic-dev-ai]

6 issues found across 860 files

Note: This PR contains a large number of files. cubic only reviews up to 75 files per PR, so some files may not have been reviewed.

Prompt for AI agents (all 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="samples/client/petstore/java/restclient-springBoot4-jackson2/docs/FakeApi.md">

<violation number="1" location="samples/client/petstore/java/restclient-springBoot4-jackson2/docs/FakeApi.md:1007">
P2: The generated example uses `Arrays.asList(-efg)`, which is invalid Java syntax. The enum value "-efg" maps to `EnumClass._EFG`, so the example should reference the enum constant instead of the raw token.</violation>
</file>

<file name="modules/openapi-generator/src/main/resources/Java/libraries/restclient/pom.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/Java/libraries/restclient/pom.mustache:351">
P2: When useJackson3 is enabled, the template still includes jackson-databind-nullable, which depends on Jackson 2 (com.fasterxml.jackson.*). This will conflict with Jackson 3’s tools.jackson.* packages and can cause compilation/runtime failures. Guard this dependency for Jackson 3 or provide a compatible alternative.</violation>
</file>

<file name="samples/client/petstore/java/restclient-springBoot4-jackson2/README.md">

<violation number="1" location="samples/client/petstore/java/restclient-springBoot4-jackson2/README.md:100">
P2: README example uses `HttpStatusCodeException` without importing it, so the snippet won’t compile when copied.</violation>
</file>

<file name="samples/client/petstore/java/restclient-springBoot4-jackson2/build.sbt">

<violation number="1" location="samples/client/petstore/java/restclient-springBoot4-jackson2/build.sbt:1">
P2: Invalid comment syntax in build.sbt; '#' is not a Scala comment and will cause sbt parsing to fail.</violation>
</file>

<file name="modules/openapi-generator/src/main/resources/Java/libraries/webclient/ApiClient.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/Java/libraries/webclient/ApiClient.mustache:169">
P2: Jackson 3 createDefaultMapper omits JsonNullableModule registration, so openApiNullable types won’t serialize/deserialize correctly.</violation>
</file>

<file name="modules/openapi-generator/src/main/resources/Java/libraries/restclient/ApiClient.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/Java/libraries/restclient/ApiClient.mustache:195">
P2: Jackson3 createDefaultMapper builds a JsonMapper without registering JsonNullableModule when openApiNullable is enabled, unlike the Jackson2 branch. JsonNullable requires its module to be registered to serialize/deserialize nullable fields, so Jackson3-generated clients will mishandle JsonNullable values.</violation>
</file>

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