@Override
    public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
      synchronized (mutex) {
        return delegate().contains(rowKey, columnKey);
      }
    }

    @Override
    public boolean containsRow(@CheckForNull Object rowKey) {
      synchronized (mutex) {
        return delegate().containsRow(rowKey);
      }
    }

    @Override

    @Override
    public boolean containsRow(Object rowKey) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.containsRow(rowKey);
    }

    @Override
    public @Nullable V get(Object rowKey, Object columnKey) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.get(rowKey, columnKey);
    }

    @Override
    public @Nullable V put(R rowKey, C columnKey, V value) {

    return headMap(toKey, false);
  }

  /**
   * This method returns a {@code ImmutableSortedMap}, consisting of the entries whose keys are less
   * than (or equal to, if {@code inclusive}) {@code toKey}.
   *
   * <p>The {@link SortedMap#headMap} documentation states that a submap of a submap throws an
   * {@link IllegalArgumentException} if passed a {@code toKey} greater than an earlier {@code

 * requirement that existing callers already fulfill).
 *
 * Disclaimer: Part of the reason that callers are so well adapted to `Function<A, B>` may be that
 * that is how the signature looked even prior to this comment! So naturally any change can break
 * existing users, but it can't *fix* existing users because any users who needed

  /**
   * {@inheritDoc}
   *
   * @throws NullPointerException if {@code rowKey} is {@code null}
   */
  @Override
  public ImmutableMap<C, V> row(R rowKey) {
    checkNotNull(rowKey, "rowKey");
    return MoreObjects.firstNonNull(
        (ImmutableMap<C, V>) rowMap().get(rowKey), ImmutableMap.<C, V>of());
  }

  @Override
  public ImmutableSet<R> rowKeySet() {

   * {@code co.uk}, {@code google.invalid}, or {@code blogspot.com}.
   *
   * <p>This method can be used to determine whether it will probably be possible to set cookies on
   * the domain, though even that depends on individual browsers' implementations of cookie
   * controls. See <a href="http://www.ietf.org/rfc/rfc2109.txt">RFC 2109</a> for details.
   *
   * @since 6.0
   */
  public boolean isUnderPublicSuffix() {

  }

  /**
   * Updates the index an iterator is pointing to after a call to remove: returns the index of the
   * entry that should be looked at after a removal on indexRemoved, with indexBeforeRemove as the
   * index that *was* the next entry that would be looked at.
   */
  int adjustAfterRemove(int indexBeforeRemove, @SuppressWarnings("unused") int indexRemoved) {
    return indexBeforeRemove - 1;
  }

    @Override
    public boolean containsRow(Object rowKey) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.containsRow(rowKey);
    }

    @Override
    public @Nullable V get(Object rowKey, Object columnKey) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.get(rowKey, columnKey);
    }

    @Override
    public @Nullable V put(R rowKey, C columnKey, V value) {

    public SortedMap<C, V> subMap(C fromKey, C toKey) {
      checkArgument(rangeContains(checkNotNull(fromKey)) && rangeContains(checkNotNull(toKey)));
      return new TreeRow(rowKey, fromKey, toKey);
    }

    @Override
    public SortedMap<C, V> headMap(C toKey) {
      checkArgument(rangeContains(checkNotNull(toKey)));
      return new TreeRow(rowKey, lowerBound, toKey);
    }

    @Override

   *
   * @throws IllegalArgumentException if {@code rowKey} is not in {@link #rowKeySet()} or {@code
   *     columnKey} is not in {@link #columnKeySet()}.
   */
  @CanIgnoreReturnValue
  @Override
  @CheckForNull
  public V put(R rowKey, C columnKey, @CheckForNull V value) {
    checkNotNull(rowKey);
    checkNotNull(columnKey);
    Integer rowIndex = rowKeyToIndex.get(rowKey);