MavenModuleSetBuild.mavenArtifatcs is supposed to return the build's MavenAggregatedArtifactRecord, but is always null

The cause is maven artifacts are recorder asynchronously (https://github.com/jenkinsci/maven-plugin/blob/master/src/main/java/hudson/maven/reporters/MavenArtifactArchiver.java#L128)
and then MavenModuleSetBuild can't see the created MavenArtifactRecord, so never add the MavenAggregatedArtifactRecord action to the build.