}
    try {
      unmod.computeIfPresent(4, (k, v) -> v);
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {
    }
    try {
      unmod.compute(4, (k, v) -> v);
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {
    }
    try {
      unmod.merge(4, "four", (k, v) -> v);

 * }
 * }</pre>
 *
 * <p>would be flagged as having called {@code sqrt()} with an illegal argument.
 *
 * <h3>Performance</h3>
 *
 * <p>Avoid passing message arguments that are expensive to compute; your code will always compute
 * them, even though they usually won't be needed. If you have such arguments, use the conventional
 * if/throw idiom instead.
 *

   * if {@code n == 0}.
   *
   * <p><b>Warning:</b> the result takes <i>O(n log n)</i> space, so use cautiously.
   *
   * <p>This uses an efficient binary recursive algorithm to compute the factorial with balanced
   * multiplies. It also removes all the 2s from the intermediate products (shifting them back in at
   * the end).
   *
   * @throws IllegalArgumentException if {@code n < 0}
   */

        this.bitsPerChar = log2(chars.length, UNNECESSARY);
      } catch (ArithmeticException e) {
        throw new IllegalArgumentException("Illegal alphabet length " + chars.length, e);
      }

      // Compute how input bytes are chunked. For example, with base64 we chunk every 3 bytes into
      // 4 characters. We have bitsPerChar == 6, charsPerChunk == 4, and bytesPerChunk == 3.

/**
 * A multiset which maintains the ordering of its elements, according to either their natural order
 * or an explicit {@link Comparator}. In all cases, this implementation uses {@link
 * Comparable#compareTo} or {@link Comparator#compare} instead of {@link Object#equals} to determine
 * equivalence of instances.
 *
 * <p><b>Warning:</b> The comparison must be <i>consistent with equals</i> as explained by the

    Predicate<String> trimEqualsFoo = Predicates.compose(equalsFoo, trim);
    Function<String, String> identity = Functions.identity();

    assertTrue(trimEqualsFoo.apply("Foo"));
    assertTrue(trimEqualsFoo.apply("   Foo   "));
    assertFalse(trimEqualsFoo.apply("Foo-b-que"));

    new EqualsTester()
        .addEqualityGroup(trimEqualsFoo, Predicates.compose(equalsFoo, trim))
        .addEqualityGroup(equalsFoo)

      // Because Supplier is read-heavy, we use the "double-checked locking" pattern.
      if (delegate != SUCCESSFULLY_COMPUTED) {
        synchronized (this) {
          if (delegate != SUCCESSFULLY_COMPUTED) {
            T t = delegate.get();
            value = t;
            delegate = (Supplier<T>) SUCCESSFULLY_COMPUTED;
            return t;
          }
        }
      }
      // This is safe because we checked `delegate`.

   * Generation, described in Knuth's "The Art of Computer Programming", Volume 4, Chapter 7,
   * Section 7.2.1.2. The iteration order follows the lexicographical order. This means that the
   * first permutation will be in ascending order, and the last will be in descending order.
   *
   * <p>Elements that compare equal are considered equal and no new permutations are created by
   * swapping them.
   *

   * @deprecated Unsupported operation.
   */
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  @CheckForNull
  public final V compute(
      K key, BiFunction<? super K, ? super @Nullable V, ? extends @Nullable V> remappingFunction) {
    throw new UnsupportedOperationException();
  }

  /**

    listener = queuingRemovalListener();
  }

  public void testGet() {
    Object computed = new Object();
    LoadingCache<Object, Object> cache =
        CacheBuilder.newBuilder()
            .maximumSize(0)
            .removalListener(listener)
            .build(constantLoader(computed));

    Object key = new Object();
    assertSame(computed, cache.getUnchecked(key));