Jackson 3

[Rattlyy]

Spring Boot no longer uses jackson 2, and that causes massive problems to all the modules that do classpath based lookups to determine which jackson to use.

[balamurugana]

Looked into what fixing this (migrating to Jackson 3) would actually involve here, cross-checked against the current Jackson usage in this codebase:

Yes — a straight migration to Jackson 3 would break things, on multiple independent axes:

1. Java 8 compatibility, violated. Jackson 3.x requires Java 17 at runtime for every artifact except jackson-annotations. This project's public API is required to stay Java 8 source/bytecode compatible (built with --release 8). Moving to Jackson 3 would force a Java 17 floor on every consumer — a deliberate compatibility regression, not a routine bump.

2. Group ID + package rename, not a version bump. Jackson 3 renames the Maven group com.fasterxml.jackson → tools.jackson and the Java packages for jackson-core/jackson-databind to tools.jackson.* (only jackson-annotations keeps the old com.fasterxml.jackson namespace). This library imports com.fasterxml.jackson.core.*/databind.* across ~29 files in api and adminapi (ObjectMapper, JsonMapper, JsonNode, DeserializationFeature, MapperFeature, CollectionType, MapType, JsonFactory, JsonParseException, JsonProcessingException). That's a full import rewrite, not a dependency version bump.

3. Jackson types leak into the public API — the concrete breaking-change risk:

   • BaseS3Client.OBJECT_MAPPER (api/src/main/java/io/minio/BaseS3Client.java) is a protected static final ObjectMapper field. BaseS3Client is public abstract, and MinioAsyncClient (also public, not final) extends it — so external subclasses can see and reference this field today. Renaming the type would break their compilation.
   • PutObjectFanOutArgs.fanOutList() (api/src/main/java/io/minio/PutObjectFanOutArgs.java) is a public method declared throws JsonProcessingException — a Jackson type baked directly into a checked-exception contract callers must handle.
   • MinioException.throwEncapsulatedException() (api/src/main/java/io/minio/errors/MinioException.java) is public and lists JsonMappingException, JsonParseException, JsonProcessingException directly in its throws clause. This method is used to unwrap async exceptions and is on the hot path for essentially every caller.

4. jackson-datatype-jsr310 is folded into jackson-databind in v3 — adminapi/MinioAdminClient.java explicitly imports JavaTimeModule and registers it; that dependency/import pattern would also need rework.

One mitigating factor: there are no custom JsonSerializer/JsonDeserializer subclasses in the codebase, so the Jackson 3 class renames (JsonDeserializer→ValueDeserializer, Module→JacksonModule, etc.) don't hit any custom code here — but that doesn't offset points 1–3.

Bottom line: a straight migration to Jackson 3 would be a breaking change for this library itself (Java 8 support dropped) and for downstream consumers who subclass BaseS3Client/MinioAsyncClient or catch the Jackson exception types this library's own public methods declare. It isn't a safe drop-in fix — it would need a major version bump here and a plan for removing Jackson from the public surface first (or shading it) rather than swapping the dependency in place.