long b = rotateRight(a + z, 52);
    long c = rotateRight(a, 37);
    a += load64(bytes, offset + 8);
    c += rotateRight(a, 7);
    a += load64(bytes, offset + 16);
    long vf = a + z;
    long vs = b + rotateRight(a, 31) + c;
    a = load64(bytes, offset + 16) + load64(bytes, offset + length - 32);
    z = load64(bytes, offset + length - 8);
    b = rotateRight(a + z, 52);
    c = rotateRight(a, 37);

    assertThat(multimap.keySet()).containsExactly("d", "c", "b", "a").inOrder();
    assertThat(multimap.values()).containsExactly(2, 4, 3, 6, 5, 2).inOrder();
    assertThat(multimap.get("a")).containsExactly(5, 2).inOrder();
    assertThat(multimap.get("b")).containsExactly(3, 6).inOrder();
    assertFalse(multimap.get("a") instanceof ImmutableSortedSet);
    assertFalse(multimap.get("x") instanceof ImmutableSortedSet);

    assertThat(multimap.keySet()).containsExactly("d", "c", "b", "a").inOrder();
    assertThat(multimap.values()).containsExactly(2, 4, 3, 6, 5, 2).inOrder();
    assertThat(multimap.get("a")).containsExactly(5, 2).inOrder();
    assertThat(multimap.get("b")).containsExactly(3, 6).inOrder();
  }

  public void testBuilderOrderKeysByDuplicates() {

    long b = rotateRight(a + z, 52);
    long c = rotateRight(a, 37);
    a += load64(bytes, offset + 8);
    c += rotateRight(a, 7);
    a += load64(bytes, offset + 16);
    long vf = a + z;
    long vs = b + rotateRight(a, 31) + c;
    a = load64(bytes, offset + 16) + load64(bytes, offset + length - 32);
    z = load64(bytes, offset + length - 8);
    b = rotateRight(a + z, 52);
    c = rotateRight(a, 37);

    assertThat(multimap.keySet()).containsExactly("d", "c", "b", "a").inOrder();
    assertThat(multimap.values()).containsExactly(2, 4, 3, 6, 5, 2).inOrder();
    assertThat(multimap.get("a")).containsExactly(5, 2).inOrder();
    assertThat(multimap.get("b")).containsExactly(3, 6).inOrder();
    assertFalse(multimap.get("a") instanceof ImmutableSortedSet);
    assertFalse(multimap.get("x") instanceof ImmutableSortedSet);

      for (String hexPrefix : ImmutableList.of("0x", "0X")) {
        for (String iPart : ImmutableList.of("", "0", "1", "F", "f", "c4", "CE")) {
          for (String fPart : ImmutableList.of("", ".", ".F", ".52", ".a")) {
            for (String expMarker : ImmutableList.of("p", "P")) {
              for (String exponent : ImmutableList.of("0", "-5", "+20", "52")) {

      for (String hexPrefix : ImmutableList.of("0x", "0X")) {
        for (String iPart : ImmutableList.of("", "0", "1", "F", "f", "c4", "CE")) {
          for (String fPart : ImmutableList.of("", ".", ".F", ".52", ".a")) {
            for (String expMarker : ImmutableList.of("p", "P")) {
              for (String exponent : ImmutableList.of("0", "-5", "+20", "52")) {

      for (String hexPrefix : ImmutableList.of("0x", "0X")) {
        for (String iPart : ImmutableList.of("", "0", "1", "F", "f", "c4", "CE")) {
          for (String fPart : ImmutableList.of("", ".", ".F", ".52", ".a")) {
            for (String expMarker : ImmutableList.of("p", "P")) {
              for (String exponent : ImmutableList.of("0", "-5", "+20", "52")) {

      for (String hexPrefix : ImmutableList.of("0x", "0X")) {
        for (String iPart : ImmutableList.of("", "0", "1", "F", "f", "c4", "CE")) {
          for (String fPart : ImmutableList.of("", ".", ".F", ".52", ".a")) {
            for (String expMarker : ImmutableList.of("p", "P")) {
              for (String exponent : ImmutableList.of("0", "-5", "+20", "52")) {

    }
    if (n < 66) {
      // Encode all primes less than 66 into mask without 0 and 1.
      long mask =
          (1L << (2 - 2))
              | (1L << (3 - 2))
              | (1L << (5 - 2))
              | (1L << (7 - 2))
              | (1L << (11 - 2))
              | (1L << (13 - 2))
              | (1L << (17 - 2))
              | (1L << (19 - 2))
              | (1L << (23 - 2))