Publish thin main jar; move fat jar to shaded classifier

[stefanhahmann]

Summary

The maven-shade-plugin in the pom.xml currently replaces the main artifact with a fat jar and publishes a dependency-reduced POM. Library consumers therefore receive a jar bundling jackson-*, aws-sdk:s3, okhttp, commons-compress, etc., paired with a POM that declares no runtime dependencies.

When a downstream project depends on dev.zarr:zarr-java and also directly on any of those libraries (very common — e.g. Jackson is ubiquitous), maven-enforcer-plugin's duplicate-class / upper-bound-deps rules fail the build because the same classes appear both inside the shaded zarr-java jar and on the regular classpath. There is no clean way for the consumer to exclude them, since the POM hides the bundled coordinates.

Change

Switch the shade execution to attach the fat jar under a classifier rather than replacing the main artifact, and disable the dependency-reduced POM:

   <shadedArtifactAttached>true</shadedArtifactAttached>                                                                                                                                                                                                                                                          
   <shadedClassifierName>shaded</shadedClassifierName>                                                                                                                                                                                                                                                          
   <createDependencyReducedPom>false</createDependencyReducedPom>  

Released artifacts after this change:

artifact	contents	intended use
zarr-java-.jar	only dev.zarr.* classes; full POM with normal	library consumers (Maven/Gradle)
zarr-java--shaded.jar	fat jar with Main-Class: dev.zarr.zarrjava.cli.Main	CLI users (java -jar …-shaded.jar)

CLI users who want the executable jar from Maven Central can pull it with shaded.

Verified locally

   - mvn -DskipTests package produces both jars.                                                                                                                                                                                                                                                                  
   - Thin jar contains only META-INF/ and dev/ (no bundled deps).
   - Shaded jar still has Main-Class: dev.zarr.zarrjava.cli.Main in its manifest.      

Notes / non-goals

• Native libraries are unaffected: zstd-jni ships its own natives inside its jar (transitively resolved via the thin POM), and blosc-java continues to require the system libblosc library on the host (as already documented in .github/workflows/deploy.yml).
• No relocations are added. The shaded jar still bundles unrelocated com.fasterxml.jackson etc.; that's fine for the CLI use case and matches today's behavior.

[sbesson]

Thanks for identifying this regression and opening a fix @stefanhahmann. Indeed, the size of the JAR published to Maven Central exploded in the 0.1.2 release (which arguably should have been released as 0.2.0).

With this PR included, the uberJAR is generated with the -shaded classifier

sbesson@Sebastien-GS-MacBook-Pro-2025 jar-Linux % ls -alh
total 89176
drwx------@  5 sbesson  staff   160B  1 May 16:52 .
drwx------@ 15 sbesson  staff   480B  1 May 16:52 ..
-rw-r--r--@  1 sbesson  staff   1.3M 30 Apr 08:51 zarr-java-0.1.3-SNAPSHOT-javadoc.jar
-rw-r--r--@  1 sbesson  staff    42M 30 Apr 08:51 zarr-java-0.1.3-SNAPSHOT-shaded.jar
-rw-r--r--@  1 sbesson  staff   270K 30 Apr 08:51 zarr-java-0.1.3-SNAPSHOT.jar