Maven 4 compatibility / Maven 3.9 warnings

[OrangeDog]

Maven 3.9.2 reports the following issues:

[WARNING]  * org.jacoco:jacoco-maven-plugin:0.8.10
[WARNING]   Plugin issue(s):
[WARNING]    * Plugin is a Maven 2.x plugin, which will be not supported in Maven 4.x
[WARNING]    * Plugin mixes multiple Maven versions: [3.0, 2.0.2]
[WARNING]    * Plugin should declare these Maven artifacts in `provided` scope: [org.apache.maven:maven-repository-metadata:3.0, org.apache.maven:maven-artifact:3.0]
[WARNING]    * Plugin depends on plexus-container-default, which is EOL

[ascopes]

Reproduce this with details by setting:

MAVEN_OPTS+=" -Dmaven.plugin.validation=verbose"

...before running Maven

[Godin]

@marchof AFAICS this is caused by transitive dependencies of org.apache.maven.shared:file-management:1.2.1, which is used by our MergeMojo

[INFO] +- org.apache.maven.shared:file-management:jar:1.2.1:compile
[INFO] |  +- org.apache.maven.shared:maven-shared-io:jar:1.1:compile
[INFO] |  |  +- org.apache.maven:maven-artifact:jar:3.0:compile
[INFO] |  |  +- org.apache.maven:maven-artifact-manager:jar:2.0.2:compile
[INFO] |  |  |  \- org.apache.maven:maven-repository-metadata:jar:3.0:compile
[INFO] |  |  \- org.apache.maven.wagon:wagon-provider-api:jar:1.0-alpha-6:compile
[INFO] |  \- org.codehaus.plexus:plexus-container-default:jar:1.0-alpha-9:compile
[INFO] |     +- junit:junit:jar:4.13.1:compile (version managed from 3.8.1)
[INFO] |     |  \- org.hamcrest:hamcrest-core:jar:1.3:compile
[INFO] |     \- classworlds:classworlds:jar:1.1-alpha-2:compile

however seems that these transitive dependencies are not needed - I drafted exclusions in #1438 and all tests pass.

Another option to solve this - is to update org.apache.maven.shared:file-management to version 3.1.0, but it requires Java 8, whereas jacoco-maven-plugin currently requires Java 5.

@marchof WDYT? maybe it's time to require Java 8 for the execution of jacoco-maven-plugin as like all core Maven plugins do nowadays ( see https://maven.apache.org/developers/compatibility-plan.html and https://ci-maven.apache.org/job/Maven/job/maven-box/job/maven-dist-tool/job/master/530/site/ ) ? note that users still will be able to execute tests with lower Java versions using maven-toolchains-plugin.

[OrangeDog]

maybe it's time to require Java 8

I agree. A lot of stuff is already migrating to Java 11 minimum.

[hazendaz]

Who is using java 5? Java 8 at very minimum should be required. Do note when updating to file-management, if you pass a logger to it from maven itself, call the constructor instead (with no logger) as it uses slf4j internally which conflicts with how maven has that obfuscated.

[joergsesterhenn]

@Godin Any idea when this will be released?

[Godin]

@joergsesterhenn See https://www.jacoco.org/jacoco/trunk/doc/faq.html

When will feature X be released?

JaCoCo is maintained by volunteers in their free time. Since we cannot guarantee free capacity, we do not commit to particular release dates. Typically, you can expect a couple of releases every year.

In the change log, you can see all features that have been implemented in master branch and will be available with the next release. And in the meantime you can test latest build of master branch (Maven SNAPSHOT) and provide feedback to us.

[OrangeDog]

Just to confuse matters, Maven 3.9.3 has a bug that means it fails to detect issues in this plugin.
https://issues.apache.org/jira/browse/MNG-7826