assertEquals(2, (int) enumer.nextElement());
    assertTrue(enumer.hasMoreElements());
    assertEquals(3, (int) enumer.nextElement());
    assertFalse(enumer.hasMoreElements());
  }

  // We're testing our asEnumeration method against a known-good implementation.
  @SuppressWarnings("JdkObsolete")
  private static Enumeration<Integer> enumerate(int... ints) {

        Set<String> packages = new LinkedHashSet<>();

        try {
            Enumeration<URL> urls = loader.getResources(BUILDER.getExtensionDescriptorLocation());
            while (urls.hasMoreElements()) {

                try (InputStream is = urls.nextElement().openStream()) {
                    ExtensionDescriptor descriptor = BUILDER.build(is);

    TestSuite candidateTests = new TestSuite(testerClass);
    TestSuite suite = filterSuite(candidateTests);

    Enumeration<?> allTests = suite.tests();
    while (allTests.hasMoreElements()) {
      Object test = allTests.nextElement();
      if (test instanceof AbstractTester) {
        @SuppressWarnings("unchecked")
        AbstractTester<? super G> tester = (AbstractTester<? super G>) test;

        try {
            Enumeration<URL> resources =
                    Slf4jConfigurationFactory.class.getClassLoader().getResources(RESOURCE);

            while (resources.hasMoreElements()) {
                URL resource = resources.nextElement();
                try {
                    InputStream is = resource.openStream();
                    final Properties properties = new Properties();

    TestSuite candidateTests = new TestSuite(testerClass);
    TestSuite suite = filterSuite(candidateTests);

    Enumeration<?> allTests = suite.tests();
    while (allTests.hasMoreElements()) {
      Object test = allTests.nextElement();
      if (test instanceof AbstractTester) {
        @SuppressWarnings("unchecked")
        AbstractTester<? super G> tester = (AbstractTester<? super G>) test;

        sp.forEach(properties::setProperty);
    }

    public static void substitute(MavenProperties props, UnaryOperator<String> callback) {
        for (Enumeration<?> e = props.propertyNames(); e.hasMoreElements(); ) {
            String name = (String) e.nextElement();
            String value = props.getProperty(name);
            if (value == null) {
                value = callback.apply(name);
            }

        sp.forEach(properties::setProperty);
    }

    public static void substitute(MavenProperties props, UnaryOperator<String> callback) {
        for (Enumeration<?> e = props.propertyNames(); e.hasMoreElements(); ) {
            String name = (String) e.nextElement();
            String value = props.getProperty(name);
            if (value == null) {
                value = callback.apply(name);
            }

      Enumeration<T> enumeration) {
    checkNotNull(enumeration);
    return new UnmodifiableIterator<T>() {
      @Override
      public boolean hasNext() {
        return enumeration.hasMoreElements();
      }

      @Override
      @ParametricNullness
      public T next() {
        return enumeration.nextElement();
      }
    };
  }

  /**

  public static ImmutableMap<String, String> fromProperties(Properties properties) {
    ImmutableMap.Builder<String, String> builder = ImmutableMap.builder();

    for (Enumeration<?> e = properties.propertyNames(); e.hasMoreElements(); ) {
      /*
       * requireNonNull is safe because propertyNames contains only non-null elements.
       *
       * Accordingly, we have it annotated as returning `Enumeration<? extends Object>` in our

  public static ImmutableMap<String, String> fromProperties(Properties properties) {
    ImmutableMap.Builder<String, String> builder = ImmutableMap.builder();

    for (Enumeration<?> e = properties.propertyNames(); e.hasMoreElements(); ) {
      /*
       * requireNonNull is safe because propertyNames contains only non-null elements.
       *
       * Accordingly, we have it annotated as returning `Enumeration<? extends Object>` in our