Restructure Jackson modules for 1.0.0: Jackson 3 becomes jackson-dataformat-msgpack

- msgpack-jackson now hosts the Jackson 3.x integration (artifact
  jackson-dataformat-msgpack, package org.msgpack.jackson3.dataformat,
  Java 17+)
- msgpack-jackson2 hosts the Jackson 2.x integration in maintenance mode
  (artifact jackson2-dataformat-msgpack, package org.msgpack.jackson.dataformat
  unchanged, Java 8+)
- Distinct packages and artifactIds let both integrations coexist on one
  classpath for incremental migration
- Add sbt-jupiter-interface so the Jackson 2 module's JUnit 5 tests actually
  run; they had been silently skipped (0 tests detected) on main
- Fix MessagePackDataformatTestBase lifecycle annotations (JUnit 4 @Before/
  @after on JUnit 5 tests meant setup never ran)
- Restore byte-offset-as-columnNr in Jackson 2 MessagePackParser locations,
  regressed unnoticed in #903 when the deprecated JsonLocation constructor
  was replaced

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014ZZUaHusAjVx6SNu4sA42s

Author: xerial

.github/workflows/CI.yml

@@ -28,7 +28,7 @@ jobs:
               - 'project/build.properties'
               - 'msgpack-core/**'
               - 'msgpack-jackson/**'
-              - 'msgpack-jackson3/**'
+              - 'msgpack-jackson2/**'
             docs:
               - '**.md'
               - '**.txt'
@@ -83,8 +83,10 @@ jobs:
         env:
           TEST_JAVA_HOME: ${{ steps.target-jdk.outputs.path }}
         run: |
+          # msgpack-jackson (Jackson 3) requires JDK 17+; older lanes test the
+          # Java 8 compatible modules only
           if [[ ${{ matrix.java }} -lt 17 ]]; then
-            ./sbt msgpack-core/test msgpack-jackson/test
+            ./sbt msgpack-core/test msgpack-jackson2/test
           else
             ./sbt test
           fi
@@ -93,7 +95,7 @@ jobs:
           TEST_JAVA_HOME: ${{ steps.target-jdk.outputs.path }}
         run: |
           if [[ ${{ matrix.java }} -lt 17 ]]; then
-            ./sbt msgpack-core/test msgpack-jackson/test -J-Dmsgpack.universal-buffer=true
+            ./sbt msgpack-core/test msgpack-jackson2/test -J-Dmsgpack.universal-buffer=true
           else
             ./sbt test -J-Dmsgpack.universal-buffer=true
           fi

.github/workflows/release.yml

@@ -38,17 +38,17 @@ jobs:
           PGP_PASSPHRASE: ${{ secrets.PGP_PASSPHRASE }}
           TEST_JAVA_HOME: ${{ steps.jdk8.outputs.path }}
         run: |
-          ./sbt msgpack-core/publishSigned msgpack-jackson/publishSigned
-      # msgpack-jackson3 requires JDK 17+
+          ./sbt msgpack-core/publishSigned msgpack-jackson2/publishSigned
+      # msgpack-jackson (Jackson 3) requires JDK 17+
       - uses: actions/setup-java@v5
         with:
           java-version: 17
           distribution: temurin
-      - name: Build bundle for msgpack-jackson3
+      - name: Build bundle for msgpack-jackson (Jackson 3)
         env:
           PGP_PASSPHRASE: ${{ secrets.PGP_PASSPHRASE }}
         run: |
-          ./sbt msgpack-jackson3/publishSigned
+          ./sbt msgpack-jackson/publishSigned
       - name: Release to Sonatype
         env:
           SONATYPE_USERNAME: '${{ secrets.SONATYPE_USERNAME }}'

CLAUDE.md

@@ -6,7 +6,8 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 MessagePack-Java is a binary serialization library that provides a fast and compact alternative to JSON. The project consists of two main modules:
 - **msgpack-core**: Standalone MessagePack implementation with no external dependencies
-- **msgpack-jackson**: Jackson integration for object mapping capabilities
+- **msgpack-jackson**: Jackson 3.x integration for object mapping capabilities (artifact `jackson-dataformat-msgpack`, Java 17+)
+- **msgpack-jackson2**: Jackson 2.x integration in maintenance mode (artifact `jackson2-dataformat-msgpack`, Java 8+)
 
 ## Essential Development Commands
 
@@ -49,7 +50,8 @@ The main entry point is the `MessagePack` factory class which creates:
 
 Key locations:
 - Core interfaces: `msgpack-core/src/main/java/org/msgpack/core/`
-- Jackson integration: `msgpack-jackson/src/main/java/org/msgpack/jackson/dataformat/`
+- Jackson 3 integration: `msgpack-jackson/src/main/java/org/msgpack/jackson3/dataformat/`
+- Jackson 2 integration: `msgpack-jackson2/src/main/java/org/msgpack/jackson/dataformat/`
 
 ### Buffer Management System
 MessagePack uses an efficient buffer abstraction layer:
@@ -68,8 +70,8 @@ The msgpack-jackson module provides:
 ### Testing Structure
 - **msgpack-core tests**: Written in Scala (always use the latest Scala 3 version) using AirSpec framework
   - Location: `msgpack-core/src/test/scala/`
-- **msgpack-jackson tests**: Written in Java using JUnit
-  - Location: `msgpack-jackson/src/test/java/`
+- **msgpack-jackson / msgpack-jackson2 tests**: Written in Java using JUnit
+  - Location: `msgpack-jackson/src/test/java/`, `msgpack-jackson2/src/test/java/`
 
 ## Important JVM Options
 

README.md

@@ -59,10 +59,10 @@ Two artifacts are published depending on which Jackson major version your projec
 
 | Jackson version | Artifact | Requirements |
 | --- | --- | --- |
-| Jackson 2.x | [`jackson-dataformat-msgpack`](https://github.com/msgpack/msgpack-java/blob/develop/msgpack-jackson/README.md) | Java 8+ |
-| Jackson 3.x | [`jackson-dataformat-msgpack-jackson3`](https://github.com/msgpack/msgpack-java/blob/develop/msgpack-jackson3/README.md) | Java 17+ |
+| Jackson 3.x | [`jackson-dataformat-msgpack`](https://github.com/msgpack/msgpack-java/blob/main/msgpack-jackson/README.md) (1.x) | Java 17+ |
+| Jackson 2.x | [`jackson2-dataformat-msgpack`](https://github.com/msgpack/msgpack-java/blob/main/msgpack-jackson2/README.md) (maintenance mode) | Java 8+ |
 
-Use `jackson-dataformat-msgpack` if your project still depends on Jackson 2.x, or `jackson-dataformat-msgpack-jackson3` if you've upgraded to Jackson 3.x. See each module's README for install instructions and usage details.
+Since msgpack-java 1.0.0, `jackson-dataformat-msgpack` targets Jackson 3.x. If your project still depends on Jackson 2.x, either stay on `jackson-dataformat-msgpack` 0.9.x or switch to `jackson2-dataformat-msgpack` to keep receiving msgpack-core updates (only the artifactId changes; the Java package is the same). See each module's README for install instructions and usage details.
 
 - [Release Notes](https://github.com/msgpack/msgpack-java/blob/develop/RELEASE_NOTES.md)
 
@@ -153,5 +153,6 @@ If some sporadic error happens (e.g., Sonatype timeout), rerun `sonaRelease` aga
 
 ```
 msgpack-core                 # Contains packer/unpacker implementation that never uses third-party libraries
-msgpack-jackson              # Contains jackson-dataformat-java implementation
+msgpack-jackson              # jackson-dataformat-msgpack: Jackson 3.x integration (Java 17+)
+msgpack-jackson2             # jackson2-dataformat-msgpack: Jackson 2.x integration (maintenance mode)
 ```

build.sbt

@@ -123,7 +123,8 @@ val junitInterface = "com.github.sbt"    % "junit-interface"      % "0.13.3" % "
 val isJava17Plus: Boolean = {
   val v = sys.props.getOrElse("java.specification.version", "1.8")
   // getOrElse(false): non-numeric versions (e.g. early-access "17-ea") fail safe
-  // by not compiling the jackson3 module rather than making an optimistic guess.
+  // by not compiling the Jackson 3 module (msgpack-jackson) rather than making an
+  // optimistic guess.
   if (v.startsWith("1.")) false else scala.util.Try(v.toInt >= 17).getOrElse(false)
 }
 
@@ -136,8 +137,8 @@ lazy val root = Project(id = "msgpack-java", base = file("."))
     publishLocal    := {}
   )
   .aggregate(
-    Seq[ProjectReference](msgpackCore, msgpackJackson) ++
-      (if (isJava17Plus) Seq[ProjectReference](msgpackJackson3) else Nil): _*
+    Seq[ProjectReference](msgpackCore, msgpackJackson2) ++
+      (if (isJava17Plus) Seq[ProjectReference](msgpackJackson) else Nil): _*
   )
 
 lazy val msgpackCore = Project(id = "msgpack-core", base = file("msgpack-core"))
@@ -181,33 +182,36 @@ lazy val msgpackCore = Project(id = "msgpack-core", base = file("msgpack-core"))
       )
   )
 
-lazy val msgpackJackson = Project(id = "msgpack-jackson", base = file("msgpack-jackson"))
+// Maintenance-mode module for Jackson 2.x users: Jackson 2.x dependency bumps and
+// bug fixes only. To be dropped in a future major release when Jackson 2 usage fades.
+lazy val msgpackJackson2 = Project(id = "msgpack-jackson2", base = file("msgpack-jackson2"))
   .enablePlugins(SbtOsgi)
   .settings(
     buildSettings,
-    name                        := "jackson-dataformat-msgpack",
-    description                 := "Jackson extension that adds support for MessagePack",
-    OsgiKeys.bundleSymbolicName := "org.msgpack.msgpack-jackson",
+    name                        := "jackson2-dataformat-msgpack",
+    description                 := "Jackson 2.x extension that adds support for MessagePack",
+    OsgiKeys.bundleSymbolicName := "org.msgpack.msgpack-jackson2",
     OsgiKeys.exportPackage      := Seq("org.msgpack.jackson", "org.msgpack.jackson.dataformat"),
     libraryDependencies ++=
       Seq(
         "com.fasterxml.jackson.core" % "jackson-databind" % "2.22.1",
         junitJupiter,
         junitVintage,
+        "com.github.sbt.junit" % "jupiter-interface" % JupiterKeys.jupiterVersion.value % "test",
         "org.apache.commons" % "commons-math3" % "3.6.1" % "test"
       ),
     testOptions += Tests.Argument(TestFrameworks.JUnit, "-v")
   )
   .dependsOn(msgpackCore)
 
-lazy val msgpackJackson3 = Project(id = "msgpack-jackson3", base = file("msgpack-jackson3"))
+lazy val msgpackJackson = Project(id = "msgpack-jackson", base = file("msgpack-jackson"))
   .enablePlugins(SbtOsgi, JmhPlugin)
   .settings(
     buildSettings,
-    name                        := "jackson-dataformat-msgpack-jackson3",
+    name                        := "jackson-dataformat-msgpack",
     description                 := "Jackson 3.x extension that adds support for MessagePack",
-    OsgiKeys.bundleSymbolicName := "org.msgpack.msgpack-jackson3",
-    OsgiKeys.exportPackage      := Seq("org.msgpack.jackson", "org.msgpack.jackson.dataformat"),
+    OsgiKeys.bundleSymbolicName := "org.msgpack.msgpack-jackson",
+    OsgiKeys.exportPackage      := Seq("org.msgpack.jackson3", "org.msgpack.jackson3.dataformat"),
     OsgiKeys.importPackage      := Seq("!android.os", "!sun.*"),
     Test / fork    := true,
     javacOptions   := Seq("--release", "17"),

msgpack-jackson/README.md

@@ -1,12 +1,12 @@
-# jackson-dataformat-msgpack-jackson3
+# jackson-dataformat-msgpack
 
 This Jackson 3.x extension library is a component to easily read and write [MessagePack](http://msgpack.org/) encoded data through jackson-databind API.
 
 It extends standard Jackson streaming API (`JsonFactory`, `JsonParser`, `JsonGenerator`), and as such works seamlessly with all the higher level data abstractions (data binding, tree model, and pluggable extensions).
 
-**Requirements:** Java 17+ and Jackson 3.x. For the Jackson 2.x compatible version, see [`msgpack-jackson`](../msgpack-jackson/).
+**Requirements:** Java 17+ and Jackson 3.x. This artifact supports Jackson 3.x since version 1.0.0 (version 0.9.x supported Jackson 2.x). For the Jackson 2.x compatible version, see [`jackson2-dataformat-msgpack`](../msgpack-jackson2/).
 
-**Note on imports:** Jackson 3 moved its core and databind packages from `com.fasterxml.jackson` to `tools.jackson`. User-facing annotations (`@JsonProperty`, `@JsonFormat`, etc.) remain in `com.fasterxml.jackson.annotation` for backward compatibility.
+**Note on imports:** Jackson 3 moved its core and databind packages from `com.fasterxml.jackson` to `tools.jackson`. User-facing annotations (`@JsonProperty`, `@JsonFormat`, etc.) remain in `com.fasterxml.jackson.annotation` for backward compatibility. Similarly, this library uses the `org.msgpack.jackson3.dataformat` package, while the Jackson 2.x artifact keeps `org.msgpack.jackson.dataformat` — so both artifacts can coexist on the same classpath during an incremental migration.
 
 ## Install
 
@@ -15,15 +15,15 @@ It extends standard Jackson streaming API (`JsonFactory`, `JsonParser`, `JsonGen
 ```xml
 <dependency>
   <groupId>org.msgpack</groupId>
-  <artifactId>jackson-dataformat-msgpack-jackson3</artifactId>
+  <artifactId>jackson-dataformat-msgpack</artifactId>
   <version>(version)</version>
 </dependency>
 ```
 
 ### Sbt
 
 ```scala
-libraryDependencies += "org.msgpack" % "jackson-dataformat-msgpack-jackson3" % "(version)"
+libraryDependencies += "org.msgpack" % "jackson-dataformat-msgpack" % "(version)"
 ```
 
 ### Gradle
@@ -34,7 +34,7 @@ repositories {
 }
 
 dependencies {
-    implementation 'org.msgpack:jackson-dataformat-msgpack-jackson3:(version)'
+    implementation 'org.msgpack:jackson-dataformat-msgpack:(version)'
 }
 ```
 
@@ -219,7 +219,7 @@ System.out.println(deserialized);   // => {42=Hello}
 
 ### Serialize and deserialize BigDecimal as str type internally in MessagePack format
 
-`jackson-dataformat-msgpack-jackson3` represents BigDecimal values as float type in MessagePack format by default for backward compatibility. But the default behavior could fail when handling too large value for `double` type. So we strongly recommend calling `MessagePackMapper.Builder#handleBigIntegerAndBigDecimalAsString()` to internally handle BigDecimal values as String.
+`jackson-dataformat-msgpack` represents BigDecimal values as float type in MessagePack format by default for backward compatibility. But the default behavior could fail when handling too large value for `double` type. So we strongly recommend calling `MessagePackMapper.Builder#handleBigIntegerAndBigDecimalAsString()` to internally handle BigDecimal values as String.
 
 ```java
 ObjectMapper objectMapper = MessagePackMapper.builder().handleBigIntegerAndBigDecimalAsString().build();

…dataformat/benchmark/BenchmarkState.java …dataformat/benchmark/BenchmarkState.javamsgpack-jackson/src/jmh/java/org/msgpack/jackson/dataformat/benchmark/BenchmarkState.java renamed to msgpack-jackson/src/jmh/java/org/msgpack/jackson3/dataformat/benchmark/BenchmarkState.java msgpack-jackson/src/jmh/java/org/msgpack/jackson/dataformat/benchmark/BenchmarkState.java renamed to msgpack-jackson/src/jmh/java/org/msgpack/jackson3/dataformat/benchmark/BenchmarkState.java

@@ -13,12 +13,12 @@
 //    See the License for the specific language governing permissions and
 //    limitations under the License.
 //
-package org.msgpack.jackson.dataformat.benchmark;
+package org.msgpack.jackson3.dataformat.benchmark;
 
-import org.msgpack.jackson.dataformat.MessagePackFactory;
-import org.msgpack.jackson.dataformat.MessagePackMapper;
-import org.msgpack.jackson.dataformat.benchmark.model.MediaItem;
-import org.msgpack.jackson.dataformat.benchmark.model.MediaItems;
+import org.msgpack.jackson3.dataformat.MessagePackFactory;
+import org.msgpack.jackson3.dataformat.MessagePackMapper;
+import org.msgpack.jackson3.dataformat.benchmark.model.MediaItem;
+import org.msgpack.jackson3.dataformat.benchmark.model.MediaItems;
 import org.openjdk.jmh.annotations.Scope;
 import org.openjdk.jmh.annotations.State;
 import tools.jackson.databind.ObjectMapper;

…rmat/benchmark/MsgpackReadBenchmark.java …rmat/benchmark/MsgpackReadBenchmark.javamsgpack-jackson/src/jmh/java/org/msgpack/jackson/dataformat/benchmark/MsgpackReadBenchmark.java renamed to msgpack-jackson/src/jmh/java/org/msgpack/jackson3/dataformat/benchmark/MsgpackReadBenchmark.java msgpack-jackson/src/jmh/java/org/msgpack/jackson/dataformat/benchmark/MsgpackReadBenchmark.java renamed to msgpack-jackson/src/jmh/java/org/msgpack/jackson3/dataformat/benchmark/MsgpackReadBenchmark.java

@@ -13,9 +13,9 @@
 //    See the License for the specific language governing permissions and
 //    limitations under the License.
 //
-package org.msgpack.jackson.dataformat.benchmark;
+package org.msgpack.jackson3.dataformat.benchmark;
 
-import org.msgpack.jackson.dataformat.benchmark.model.MediaItem;
+import org.msgpack.jackson3.dataformat.benchmark.model.MediaItem;
 import org.openjdk.jmh.annotations.Benchmark;
 import org.openjdk.jmh.annotations.BenchmarkMode;
 import org.openjdk.jmh.annotations.Fork;

…mat/benchmark/MsgpackWriteBenchmark.java …mat/benchmark/MsgpackWriteBenchmark.javamsgpack-jackson/src/jmh/java/org/msgpack/jackson/dataformat/benchmark/MsgpackWriteBenchmark.java renamed to msgpack-jackson/src/jmh/java/org/msgpack/jackson3/dataformat/benchmark/MsgpackWriteBenchmark.java msgpack-jackson/src/jmh/java/org/msgpack/jackson/dataformat/benchmark/MsgpackWriteBenchmark.java renamed to msgpack-jackson/src/jmh/java/org/msgpack/jackson3/dataformat/benchmark/MsgpackWriteBenchmark.java

@@ -13,10 +13,10 @@
 //    See the License for the specific language governing permissions and
 //    limitations under the License.
 //
-package org.msgpack.jackson.dataformat.benchmark;
+package org.msgpack.jackson3.dataformat.benchmark;
 
-import org.msgpack.jackson.dataformat.benchmark.model.MediaItem;
-import org.msgpack.jackson.dataformat.benchmark.model.MediaItems;
+import org.msgpack.jackson3.dataformat.benchmark.model.MediaItem;
+import org.msgpack.jackson3.dataformat.benchmark.model.MediaItems;
 import org.openjdk.jmh.annotations.Benchmark;
 import org.openjdk.jmh.annotations.BenchmarkMode;
 import org.openjdk.jmh.annotations.Fork;

…ataformat/benchmark/NopOutputStream.java …ataformat/benchmark/NopOutputStream.javamsgpack-jackson/src/jmh/java/org/msgpack/jackson/dataformat/benchmark/NopOutputStream.java renamed to msgpack-jackson/src/jmh/java/org/msgpack/jackson3/dataformat/benchmark/NopOutputStream.java msgpack-jackson/src/jmh/java/org/msgpack/jackson/dataformat/benchmark/NopOutputStream.java renamed to msgpack-jackson/src/jmh/java/org/msgpack/jackson3/dataformat/benchmark/NopOutputStream.java

@@ -13,7 +13,7 @@
 //    See the License for the specific language governing permissions and
 //    limitations under the License.
 //
-package org.msgpack.jackson.dataformat.benchmark;
+package org.msgpack.jackson3.dataformat.benchmark;
 
 import java.io.OutputStream;