openJarFile(jar).run {
            entries().asSequence()
                .filter { it.name.isClassFilePath }
                .map { kotlinSourceNameOf(it.name) }
        }

    private
    fun sourceNamesFromDir(dir: File): Sequence<String> =
        dir.walkTopDown()
            .filter { it.name.isClassFilePath }
            .map { kotlinSourceNameOf(normaliseFileSeparators(it.relativeTo(dir).path)) }

    private

                    FileVisitResult.CONTINUE

                override fun visitFile(file: Path, attrs: BasicFileAttributes): FileVisitResult {
                    when {
                        file.isClassFilePath() -> {
                            visitClassFile(file)
                        }
                        file.isBuildReceipt() -> {
                            Files.copy(file, buildReceipt)
                        }