private static ImmutableSet<File> filesUnderDirectory(File dir, Predicate<File> predicate)
      throws IOException {
    assertWithMessage(dir.toString()).that(dir.isDirectory()).isTrue();
    try (Stream<Path> paths = Files.walk(dir.toPath())) {
      return paths.map(Path::toFile).filter(predicate).collect(toImmutableSet());
    }
  }
Tests that we can compile our AutoValue tests using the Eclipse batch compiler. Since the tests
exercise many AutoValue subtleties, the ability to compile them all is a good indication of
Eclipse support.
value/src/it/functional/src/test/java/com/google/auto/value/CompileWithEclipseTest.java