* first specified. That is, if multiple elements are {@linkplain Object#equals equal}, all except
   * the first are ignored.
   */
  public static <E> ImmutableSet<E> of(E e1, E e2) {
    return construct(2, e1, e2);
  }

  /**
   * Returns an immutable set containing the given elements, minus duplicates, in the order each was

    // TODO(cpovirk): Consider using Object[] anyway.
    E[] array = (E[]) elements.toArray();
    /*
     * For a Set, we guess that it contains no duplicates. That's just a guess for purpose of
     * sizing; if the Set uses different equality semantics, it might contain duplicates according
     * to equals(), and we will deduplicate those properly, albeit at some cost in allocations.
     */
    int expectedSize =

		var res *Checksum
		for _, header := range trailing {
			var duplicates bool
			switch {
			case strings.EqualFold(header, ChecksumCRC32C.Key()):
				duplicates = res != nil
				res = NewChecksumWithType(ChecksumCRC32C|ChecksumTrailing, "")
			case strings.EqualFold(header, ChecksumCRC32.Key()):
				duplicates = res != nil
				res = NewChecksumWithType(ChecksumCRC32|ChecksumTrailing, "")

    try {
      builder.buildOrThrow();
      fail("Expected exception from duplicate keys");
    } catch (IllegalArgumentException expected) {
      // We don't really care which values the exception message contains, but they should be
      // different from each other. If buildKeepingLast() collapsed duplicates, that might end up
      // not being true.

    try {
      builder.buildOrThrow();
      fail("Expected exception from duplicate keys");
    } catch (IllegalArgumentException expected) {
      // We don't really care which values the exception message contains, but they should be
      // different from each other. If buildKeepingLast() collapsed duplicates, that might end up
      // not being true.

            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.SERIALIZABLE_INCLUDING_VIEWS,
                CollectionFeature.KNOWN_ORDER,
                MapFeature.REJECTS_DUPLICATES_AT_CREATION,
                MapFeature.ALLOWS_ANY_NULL_QUERIES)
            .named("ImmutableSortedMap")
            .createTestSuite());
    suite.addTest(

		name string
		args args
		want []string
	}{
		{
			name: "No duplicates",
			args: args{ports: []string{"1234", "2345"}},
			want: []string{"1234", "2345"},
		},
		{
			name: "Sequential Duplicates",
			args: args{ports: []string{"1234", "1234", "2345", "2345"}},
			want: []string{"1234", "2345"},
		},
		{
			name: "Mixed Duplicates",
			args: args{ports: []string{"1234", "2345", "1234", "2345"}},

  // The list ordering isn't significant, may contain duplicates, and possibly be incomplete.
  repeated ResourceRule resourceRules = 1;

  // NonResourceRules is the list of actions the subject is allowed to perform on non-resources.
  // The list ordering isn't significant, may contain duplicates, and possibly be incomplete.
  repeated NonResourceRule nonResourceRules = 2;

    }
    if (mapFeatures.contains(MapFeature.SUPPORTS_REMOVE)) {
      derivedFeatures.add(CollectionFeature.SUPPORTS_REMOVE);
    }
    if (mapFeatures.contains(MapFeature.REJECTS_DUPLICATES_AT_CREATION)) {
      derivedFeatures.add(CollectionFeature.REJECTS_DUPLICATES_AT_CREATION);
    }
    if (mapFeatures.contains(MapFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION)) {
      derivedFeatures.add(CollectionFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION);

            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.SERIALIZABLE,
                CollectionFeature.KNOWN_ORDER,
                MapFeature.REJECTS_DUPLICATES_AT_CREATION,
                MapFeature.ALLOWS_ANY_NULL_QUERIES)
            .suppressing(BiMapInverseTester.getInverseSameAfterSerializingMethods())
            .createTestSuite());
    suite.addTest(