Summary

• Introduces feign.codec.JsonDecoder interface in feign-core that extends Decoder with an additional decode(Object, Type) method for in-memory object conversion
• Provides implementations for all JSON library modules: Jackson, Jackson 3, Jackson Jr, Gson, Moshi, Fastjson2, and JSON-java (org.json)
• Rewrites GraphqlDecoder to accept a single JsonDecoder instead of directly depending on ObjectMapper, removing the jackson-databind compile dependency from the graphql module
• The JsonDecoder.decode(Object, Type) method enables direct Map-to-target-type conversion, avoiding the previous serialize-then-deserialize round-trip

All new types are annotated with @Experimental.

Test plan

• All existing graphql tests pass with JacksonJsonDecoder
• All existing tests in core, jackson, jackson3, jackson-jr, gson, moshi, fastjson2, json modules pass
• Verify CI passes on all supported JDK versions

🤖 Generated with Claude Code