// no way to find out the stream is empty without walking its spliterator
    assertThat(findLast(list.stream().mapToInt(i -> i).filter(i -> i < 0)))
        .isEqualTo(OptionalInt.empty());
  }

  public void testFindLast_longStream() {
    assertThat(findLast(LongStream.of())).isEqualTo(OptionalLong.empty());
    assertThat(findLast(LongStream.of(1, 2, 3, 4, 5))).isEqualTo(OptionalLong.of(5));

  public void testConcat() {
    assertThat(Bytes.concat()).isEqualTo(EMPTY);
    assertThat(Bytes.concat(EMPTY)).isEqualTo(EMPTY);
    assertThat(Bytes.concat(EMPTY, EMPTY, EMPTY)).isEqualTo(EMPTY);
    assertThat(Bytes.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Bytes.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Bytes.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);
    assertThat(Bytes.concat(ARRAY1, ARRAY1, ARRAY1))

    expectContents();
  }

  // retainAll(null)

  /*
   * AbstractCollection fails the retainAll(null) test when the subject
   * collection is empty, but we'd still like to test retainAll(null) when we
   * can. We split the test into empty and non-empty cases. This allows us to
   * suppress only the former.
   */

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)

  }

  public void testEmptiesFirst() {
    Optional<String> empty = Optional.empty();
    Optional<String> abc = Optional.of("abc");
    Optional<String> z = Optional.of("z");

    Comparator<Optional<String>> comparator = Comparators.emptiesFirst(comparing(String::length));
    Helpers.testComparator(comparator, empty, z, abc);

    // Just demonstrate that no explicit type parameter is required

                  protected Set<String> create(String[] elements) {
                    return Sets.union(Sets.<String>newHashSet(), Sets.<String>newHashSet());
                  }
                })
            .named("empty U empty")
            .withFeatures(
                CollectionSize.ZERO, CollectionFeature.NONE, CollectionFeature.ALLOWS_NULL_VALUES)
            .createTestSuite());

    suite.addTest(
        SetTestSuiteBuilder.using(

  }

  @GwtIncompatible // ObjectArrays.newArray(Class, int)
  public void testNewArray_fromClass_Empty() {
    String[] empty = ObjectArrays.newArray(String.class, 0);
    assertEquals(String[].class, empty.getClass());
    assertThat(empty).isEmpty();
  }

  @GwtIncompatible // ObjectArrays.newArray(Class, int)
  public void testNewArray_fromClass_Nonempty() {

                wConfig.setExcludedUrls(getDefaultString("default.config.web.excludedUrls", StringUtil.EMPTY));
                wConfig.setIncludedDocUrls(getDefaultString("default.config.web.includedDocUrls", StringUtil.EMPTY));
                wConfig.setIncludedUrls(getDefaultString("default.config.web.includedUrls", StringUtil.EMPTY));

    }

    public static String key(String groupId, String artifactId, String version) {
        notBlank(groupId, "groupId can neither be null, empty nor blank");
        notBlank(artifactId, "artifactId can neither be null, empty nor blank");
        notBlank(version, "version can neither be null, empty nor blank");

        return groupId + ":" + artifactId + ":" + version;
    }

    private static void notBlank(String str, String message) {

      }
    } catch (NoSuchElementException e) {
      throw new IllegalArgumentException(e);
    }

    boolean empty;
    if (effectiveRange.isEmpty()) {
      empty = true;
    } else {
      /*
       * requireNonNull is safe because the effectiveRange operations above would have thrown or
       * effectiveRange.isEmpty() would have returned true.
       */

  }

  private static final ImmutableMap<Class<?>, Method> EMPTY_GENERATORS;

  static {
    ImmutableMap.Builder<Class<?>, Method> builder = ImmutableMap.builder();
    for (Method method : FreshValueGenerator.class.getDeclaredMethods()) {
      if (method.isAnnotationPresent(Empty.class)) {
        builder.put(method.getReturnType(), method);
      }
    }
    EMPTY_GENERATORS = builder.buildOrThrow();
  }