RFR: 8164805: Fail to create a MR modular JAR with a versioned entry in base-versioned empty package

[Steve Drach]

>  76     private String files(Path start) throws IOException {
> Perhaps return Stream<String>.  That can replace the unnecessary concat in a String and then later split to pass to javac.

Is this better?

    private void javac(Path source, Path destination) throws IOException {
        Stream<String> prefix = Stream.of("-d", destination.toString());
        Stream<String> suffix = Files.isDirectory(source)
                ? Files.walk(source)
                       .map(Path::toString)
                       .filter(s -> s.endsWith(".java"))
                : Stream.of(source.toString());
        String[] args = Stream.concat(prefix, suffix).toArray(String[]::new);
        JAVAC_TOOL.run(System.out, System.err, args);
    }