build-system/tests/customArtifactDep/util/build.gradle

apply plugin: 'java'

configurations {
    custom
}

sourceSets {
    custom {
        java {
            srcDirs = ['src/custom/java']
        }
    }
}

task customJar(type: Jar) {
    from sourceSets.custom.output
    classifier "custom"
}

// declare the new artifact
artifacts {
    custom customJar
}