byte[] code = new byte[4];
        Encdec.enc_uint32le(2, code, 0);
        byte[] codeHmac = getHmac(code, key.getEncoded());

        byte[] dataChecksum = new byte[KerberosConstants.CHECKSUM_SIZE];
        System.arraycopy(data, 0, dataChecksum, 0, KerberosConstants.CHECKSUM_SIZE);

        byte[] dataHmac = getHmac(dataChecksum, codeHmac);
        SecretKeySpec dataKey = new SecretKeySpec(dataHmac, KerberosConstants.RC4_ALGORITHM);

  private final Key key;

  private final String toString;
  private final int bits;
  private final boolean supportsClone;

  MacHashFunction(String algorithmName, Key key, String toString) {
    this.prototype = getMac(algorithmName, key);
    this.key = checkNotNull(key);
    this.toString = checkNotNull(toString);
    this.bits = prototype.getMacLength() * Byte.SIZE;
    this.supportsClone = supportsClone(prototype);
  }

    getMap().forcePut(null, v1());

    expectContents(mapEntry((K) null, v1()));

    assertFalse(getMap().containsValue(v0()));

    assertTrue(getMap().containsValue(v1()));
    assertTrue(getMap().inverse().containsKey(v1()));
    assertNull(getMap().inverse().get(v1()));
    assertEquals(v1(), getMap().get(null));
    assertEquals(1, getMap().size());
  }

  @CollectionSize.Require(absent = ZERO)
  public void testRemove_present() {
    int initialSize = getMap().size();
    assertEquals("remove(present) should return the associated value", v0(), getMap().remove(k0()));
    assertEquals(
        "remove(present) should decrease a map's size by one.", initialSize - 1, getMap().size());
    expectMissing(e0());
  }

    getMap().forcePut(null, v1());

    expectContents(mapEntry((K) null, v1()));

    assertFalse(getMap().containsValue(v0()));

    assertTrue(getMap().containsValue(v1()));
    assertTrue(getMap().inverse().containsKey(v1()));
    assertNull(getMap().inverse().get(v1()));
    assertEquals(v1(), getMap().get(null));
    assertEquals(1, getMap().size());
  }

  public void testKeySetIteratorRemove() {
    int initialSize = getNumElements();
    Iterator<K> iterator = getMap().keySet().iterator();
    iterator.next();
    iterator.remove();
    assertEquals(initialSize - 1, getMap().size());
    assertEquals(initialSize - 1, getMap().inverse().size());
  }

public class ConcurrentMapReplaceTester<K, V> extends AbstractMapTester<K, V> {
  @Override
  protected ConcurrentMap<K, V> getMap() {
    return (ConcurrentMap<K, V>) super.getMap();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testReplace_supportedPresent() {
    assertEquals(v0(), getMap().replace(k0(), v3()));
    expectReplacement(entry(k0(), v3()));
  }

  @MapFeature.Require(SUPPORTS_PUT)

    assertFalse(
        "Maps of different sizes should not be equal.", getMap().equals(newHashMap(moreEntries)));
  }

  public void testEquals_list() {
    assertFalse(
        "A List should never equal a Map.", getMap().equals(copyToList(getMap().entrySet())));
  }

  private static <K, V> Map<K, V> newHashMap(

    assertTrue(getMap().remove(k0(), v0()));
    expectMissing(e0());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testRemove_supportedPresentKeyWrongValue() {
    assertFalse(getMap().remove(k0(), v3()));
    expectUnchanged();
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testRemove_supportedWrongKeyPresentValue() {
    assertFalse(getMap().remove(k3(), v0()));

    assertTrue("containsKey(present) should return true", getMap().containsKey(k0()));
  }

  public void testContains_no() {
    assertFalse("containsKey(notPresent) should return false", getMap().containsKey(k3()));
  }

  @MapFeature.Require(ALLOWS_NULL_KEY_QUERIES)
  public void testContains_nullNotContainedButAllowed() {
    assertFalse("containsKey(null) should return false", getMap().containsKey(null));
  }