[deploy] Cannot handle aar as packaging (Unknown packaging: aar)

[Deishelon]

Android libraries use <packaging>aar</packaging> which causes an exception inside of pomchecker

[ERROR] Unknown packaging: aar @ line 13, column 14

Full trace:

[INFO]  JReleaser 1.16.0
[INFO]    - basedir set to [REDACTED]
[INFO]    - outputdir set to /home/[REDACTED]/projects/[REDACTED]/[REDACTED]/build/jreleaser
[INFO]  git-root-search set to true
[INFO]  Loading variables from /home/[REDACTED]/.jreleaser/config.properties
[WARN]  Variables source /home/[REDACTED]/.jreleaser/config.properties does not exist
[INFO]  Validating configuration
[INFO]  Strict mode set to false
[INFO]  Project version set to [REDACTED]
[INFO]  Release is not snapshot
[INFO]  Timestamp is 2025-02-07T17:41:59.031565807+13:00
[INFO]  HEAD is at [REDACTED]
[INFO]  Platform is linux-x86_64
[INFO]  dry-run set to false
[INFO]  Deploying Maven artifacts
[INFO]    [maven] Deploying all staged artifacts
[INFO]      [mavenCentral] Deploying to sonatype
[INFO]      [mavenCentral] Verifying prerequisites
[INFO]      [mavenCentral] Verifying POMs
[ERROR]     [mavenCentral] PomChecker detected errors in [REDACTED].pom
org.apache.maven.project.ProjectBuildingException: Some problems were encountered while processing the POMs:
[ERROR] Unknown packaging: aar @ line 13, column 14
[INFO]  Writing output properties to build/jreleaser/output.properties
[ERROR] JReleaser failed after 0.668 s

And:

[ERROR]     [mavenCentral] java.lang.IllegalStateException: org.apache.maven.project.ProjectBuildingException: Some problems were encountered while processing the POMs:
[ERROR]     [mavenCentral] [ERROR] Unknown packaging: aar @ line 13, column 14
[ERROR]     [mavenCentral] 
[ERROR]     [mavenCentral]     at org.kordamp.maven.checker.cli.internal.PomParser.createMavenProject(PomParser.java:114)
[ERROR]     [mavenCentral]     at org.kordamp.maven.checker.cli.internal.PomParser.createMavenProject(PomParser.java:78)
[ERROR]     [mavenCentral]     at org.kordamp.maven.checker.cli.CheckMavenCentral.execute(CheckMavenCentral.java:61)
[ERROR]     [mavenCentral]     at org.kordamp.maven.checker.cli.AbstractCommand.call(AbstractCommand.java:108)
[ERROR]     [mavenCentral]     at org.kordamp.maven.checker.cli.CheckMavenCentral.call(CheckMavenCentral.java:30)
[ERROR]     [mavenCentral]     at org.kordamp.maven.checker.cli.AbstractCommand.call(AbstractCommand.java:35)
[ERROR]     [mavenCentral]     at picocli.CommandLine.executeUserObject(CommandLine.java:2041)
[ERROR]     [mavenCentral]     at picocli.CommandLine.access$1500(CommandLine.java:148)
[ERROR]     [mavenCentral]     at picocli.CommandLine$RunLast.executeUserObjectOfLastSubcommandWithSameParent(CommandLine.java:2461)
[ERROR]     [mavenCentral]     at picocli.CommandLine$RunLast.handle(CommandLine.java:2453)
[ERROR]     [mavenCentral]     at picocli.CommandLine$RunLast.handle(CommandLine.java:2415)
[ERROR]     [mavenCentral]     at picocli.CommandLine$AbstractParseResultHandler.execute(CommandLine.java:2273)
[ERROR]     [mavenCentral]     at picocli.CommandLine$RunLast.execute(CommandLine.java:2417)
[ERROR]     [mavenCentral]     at picocli.CommandLine.execute(CommandLine.java:2170)
[ERROR]     [mavenCentral]     at org.kordamp.maven.checker.cli.Main.execute(Main.java:86)
[ERROR]     [mavenCentral]     at org.kordamp.maven.checker.cli.Main.run(Main.java:72)
[ERROR]     [mavenCentral]     at org.kordamp.maven.checker.cli.Main.main(Main.java:64)
[ERROR]     [mavenCentral] Caused by: org.apache.maven.project.ProjectBuildingException: Some problems were encountered while processing the POMs:
[ERROR]     [mavenCentral] [ERROR] Unknown packaging: aar @ line 13, column 14
[ERROR]     [mavenCentral] 
[ERROR]     [mavenCentral]     at org.apache.maven.project.DefaultProjectBuilder.build(DefaultProjectBuilder.java:208)
[ERROR]     [mavenCentral]     at org.apache.maven.project.DefaultProjectBuilder.build(DefaultProjectBuilder.java:123)
[ERROR]     [mavenCentral]     at org.kordamp.maven.checker.cli.internal.PomParser.createMavenProject(PomParser.java:111)
[ERROR]     [mavenCentral]     ... 16 more
[ERROR]     [mavenCentral] Caused by: org.apache.maven.model.building.ModelBuildingException: 1 problem was encountered while building the effective model for [REDACTED]
[ERROR]     [mavenCentral] [ERROR] Unknown packaging: aar @ line 13, column 14
[ERROR]     [mavenCentral] 
[ERROR]     [mavenCentral]     at org.apache.maven.model.building.DefaultModelProblemCollector.newModelBuildingException(DefaultModelProblemCollector.java:176)
[ERROR]     [mavenCentral]     at org.apache.maven.model.building.DefaultModelBuilder.build(DefaultModelBuilder.java:508)
[ERROR]     [mavenCentral]     at org.apache.maven.model.building.DefaultModelBuilder.build(DefaultModelBuilder.java:410)
[ERROR]     [mavenCentral]     at org.apache.maven.model.building.DefaultModelBuilder.build(DefaultModelBuilder.java:243)
[ERROR]     [mavenCentral]     at org.apache.maven.project.DefaultProjectBuilder.build(DefaultProjectBuilder.java:176)
[ERROR]     [mavenCentral]     ... 18 more

There is this issue in pomchecker project, kordamp/pomchecker#21
Where the author recommends to add a custom plugin. jreleaser should update its documentation to reflect how to use jreleaser with Android .aar publishing.

[jmini]

My thoughts/notes on this:

I agree with the statement in the linked issue kordamp/pomchecker#21 (comment) (it would be better to have a correct POM), this doesn't seems to be a requirement for a publication on maven central.

Somehow an XML with a packaging aar without a <build> section is valid.

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <packaging>aar</packaging>
    <!-- ... -->
</project>

If you want to do this, you can just by-pass the pomChecker validation in jreleaser.
Set verifyPom = false as documented here https://jreleaser.org/guide/latest/reference/deploy/maven/maven-central.html

I am not sure about the impact on consumer. In the android ecosystem nobody complained about those broken POM.

---

If you prefer adding a <build> section to the generated pom. This can be done with the pom.withXml { .. } section. Example:

publishing {
    publications {
        maven(MavenPublication) {
            groupId = 'com.acme'
            artifactId = 'app'

            from components.java

            pom {
                name = 'app'
                description = 'Sample application'
                url = 'https://github.com/aalmiray/app'
                inceptionYear = '2021'
                licenses {
                    license {
                        name = 'Apache-2.0'
                        url = 'https://spdx.org/licenses/Apache-2.0.html'
                    }
                }
                developers {
                    developer {
                        id = 'aalmiray'
                        name = 'Andres Almiray'
                    }
                }
                scm {
                    connection = 'scm:git:https://github.com/aalmiray/app.git'
                    developerConnection = 'scm:git:ssh://github.com/aalmiray/app.git'
                    url = 'http://github.com/aalmiray/app'
                }
                pom.withXml {
                    def buildNode = asNode().appendNode('build')
                    def pluginsNode = buildNode.appendNode('plugins')
                    def pluginNode = pluginsNode.appendNode('plugin')
                    pluginNode.appendNode('groupId', 'com.simpligility.maven.plugins')
                    pluginNode.appendNode('artifactId', 'android-maven-plugin')
                    pluginNode.appendNode('version', '4.6.0')
                    pluginNode.appendNode('extensions', 'true')
                }
            }
        }
    }

    repositories {
        maven {
            url = layout.buildDirectory.dir('staging-deploy')
        }
    }
}

This will add the recommended <plugin>..</plugin> section in the generated pom:

  <build>
    <plugins>
      <plugin>
        <groupId>com.simpligility.maven.plugins</groupId>
        <artifactId>android-maven-plugin</artifactId>
        <version>4.6.0</version>
        <extensions>true</extensions>
      </plugin>
    </plugins>
  </build>