@Override
  public boolean containsKey(@Nullable Object key) {
    if (unfiltered.containsKey(key)) {
      @SuppressWarnings("unchecked") // k is equal to a K, if not one itself
      K k = (K) key;
      return keyPredicate.apply(k);
    }
    return false;
  }

  @Override
  public Collection<V> removeAll(@Nullable Object key) {
    return containsKey(key) ? unfiltered.removeAll(key) : unmodifiableEmptyCollection();
  }

  @Override
  public boolean containsKey(@Nullable Object key) {
    if (unfiltered.containsKey(key)) {
      @SuppressWarnings("unchecked") // k is equal to a K, if not one itself
      K k = (K) key;
      return keyPredicate.apply(k);
    }
    return false;
  }

  @Override
  public Collection<V> removeAll(@Nullable Object key) {
    return containsKey(key) ? unfiltered.removeAll(key) : unmodifiableEmptyCollection();
  }

 * Null row keys, columns keys, and values are not supported.
 *
 * <p>Lookups by row key are often faster than lookups by column key, because the data is stored in
 * a {@code Map<R, Map<C, V>>}. A method call like {@code column(columnKey).get(rowKey)} still runs
 * quickly, since the row key is provided. However, {@code column(columnKey).size()} takes longer,
 * since an iteration across all row keys occurs.
 *

      assertThat(property.toString()).isEqualTo(property.key() + "=" + property.value());
    }
  }

  public void testNoNullValues() {
    for (StandardSystemProperty property : StandardSystemProperty.values()) {
      // Even though the contract in System.getProperties() specifies that a value will exist for
      // all of the listed keys, for some reason the "java.compiler" key returns null in some JVMs.
      if (property == JAVA_COMPILER) {

    CacheLoader<Integer, String> recursiveLoader =
        new CacheLoader<Integer, String>() {
          @Override
          public String load(Integer key) {
            if (key > 0) {
              return key + ", " + cacheRef.get().getUnchecked(key - 1);
            } else {
              return "0";
            }
          }
        };

    LoadingCache<Integer, String> recursiveCache =

    CacheLoader<Integer, String> recursiveLoader =
        new CacheLoader<Integer, String>() {
          @Override
          public String load(Integer key) {
            if (key > 0) {
              return key + ", " + cacheRef.get().getUnchecked(key - 1);
            } else {
              return "0";
            }
          }
        };

    LoadingCache<Integer, String> recursiveCache =

  }

  @Override
  public @Nullable Entry<K, V> floorEntry(K key) {
    return delegate.floorEntry(checkValid(key));
  }

  @Override
  public @Nullable K floorKey(K key) {
    return delegate.floorKey(checkValid(key));
  }

  @Override
  public @Nullable V get(Object key) {
    return delegate.get(checkValid(key));
  }

  @Override
  public SortedMap<K, V> headMap(K toKey) {

  @SuppressWarnings("Immutable") // keys are immutable, but not provably so
  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);

        }
        return asMap;
      }
    }

    @Override
    public Multiset<K> keys() {
      synchronized (mutex) {
        if (keys == null) {
          keys = multiset(delegate().keys(), mutex);
        }
        return keys;
      }
    }

    @Override
    // A forwarding implementation can't do any better than the underlying object.

        RenderDataUtil.register(data, "key1", null);
        assertNull(data.getDataMap().get("key1"));
    }

    @Test
    public void test_register_string() {
        RenderData data = new RenderData();
        RenderDataUtil.register(data, "key1", "test value");
        assertEquals("test value", data.getDataMap().get("key1"));

        RenderDataUtil.register(data, "key2", "");