@Override
                  protected Set<String> create(String[] elements) {
                    return union(emptySet(), emptySet());
                  }
                })
            .named("empty U empty")
            .withFeatures(CollectionSize.ZERO, CollectionFeature.ALLOWS_NULL_VALUES)
            .createTestSuite());

    suite.addTest(
        SetTestSuiteBuilder.using(

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

    }

    default void setDefaultLabelValue(final String value) {
        setSystemProperty(Constants.DEFAULT_LABEL_VALUE_PROPERTY, value);
        propMap.remove(DEFAULT_LABEL_VALUES);
    }

    default String getDefaultLabelValue() {
        return getSystemProperty(Constants.DEFAULT_LABEL_VALUE_PROPERTY, StringUtil.EMPTY);
    }

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

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

/**
 * @param {?string} str
 * @return {boolean} Whether the given string is null or is the empty string.
 * @public
 */
Platform.stringIsNullOrEmpty = function(str) {
  return !str;
};


/**
 * @param {?string} str
 * @return {string} Original str, if it is non-null. Otherwise empty string.
 */
Platform.nullToEmpty = function(str) {
  return str || "";
};


/**
 * @param {?string} str

    @Nonnull
    <T> T lookup(Class<T> type, String name);

    /**
     * Performs a lookup for optional typed component.
     *
     * @param type The component type.
     * @return Optional carrying component or empty optional if no such component.
     * @param <T> The component type.
     * @throws LookupException if there is some provisioning related issue.
     */
    @Nonnull
    <T> Optional<T> lookupOptional(Class<T> type);

  }

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

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

    // Just demonstrate that no explicit type parameter is required

     *
     * @param baseDirectory the base directory for relativizing paths during matching
     * @param includes the patterns of files to include, or null/empty for including all files
     * @param excludes the patterns of files to exclude, or null/empty for no exclusion
     * @param useDefaultExcludes whether to augment excludes with default SCM exclusion patterns

        assertArrayEquals(key, transport.getServerEncryptionKey());
        verify(transport).getServerEncryptionKey();

        // Empty array
        byte[] empty = new byte[0];
        when(transport.getServerEncryptionKey()).thenReturn(empty);
        assertArrayEquals(empty, transport.getServerEncryptionKey());

        // Null
        when(transport.getServerEncryptionKey()).thenReturn(null);