private
    fun someClassesInDefaultPackage(): Sequence<Path> {
        val directory = projectDir.resolve("classes-default")

        DEFAULT_EXCLUDES_FOR_TEST.forEachIndexed { i, pkg ->
            touchFile(directory.resolve("$pkg/Foo$i.class"))
        }

        return sequenceOf(directory)
    }

    private
    fun aJar(sourceFiles: Sequence<Path>): Sequence<Path> {