break;
        default:
          throw new AssertionError("Should never get here.");
      }
      h1 ^= mixK1(k1);
      h2 ^= mixK2(k2);
    }

    @Override
    protected HashCode makeHash() {
      h1 ^= length;
      h2 ^= length;

      h1 += h2;
      h2 += h1;

      h1 = fmix64(h1);
      h2 = fmix64(h2);

      h1 += h2;
      h2 += h1;

  }

  private static void assertNullsThrowException(Funnel<?> funnel) {
    PrimitiveSink primitiveSink =
        new AbstractStreamingHasher(4, 4) {
          @Override
          protected HashCode makeHash() {
            throw new UnsupportedOperationException();
          }

          @Override
          protected void process(ByteBuffer bb) {
            while (bb.hasRemaining()) {
              bb.get();

    }

    Sink(int chunkSize) {
      super(chunkSize);
      this.chunkSize = chunkSize;
      this.bufferSize = chunkSize;
    }

    @Override
    protected HashCode makeHash() {
      return HashCode.fromBytes(out.toByteArray());
    }

    @Override
    protected void process(ByteBuffer bb) {
      processCalled++;
      assertEquals(ByteOrder.LITTLE_ENDIAN, bb.order());

            "the number of bits (%s) in hashFunction (%s) must be divisible by 8",
            function.bits(),
            function);
      }
    }

    @Override
    HashCode makeHash(Hasher[] hashers) {
      byte[] bytes = new byte[bits() / 8];
      int i = 0;
      for (Hasher hasher : hashers) {
        HashCode newHash = hasher.hash();