*    default to their previous value.
 *
 * Every [edit] call must be matched by a call to [Editor.commit] or [Editor.abort]. Committing is
 * atomic: a read observes the full set of values as they were before or after the commit, but never
 * a mix of values.
 *
 * Clients call [get] to read a snapshot of an entry. The read will observe the value at the time

    assertNull(map.get(unmappedKey));
  }

  public void testGetNull() {
    Map<K, V> map = makeEitherMap();
    if (allowsNullKeys) {
      if (allowsNullValues) {
        // TODO: decide what to test here.
      } else {
        assertEquals(map.containsKey(null), map.get(null) != null);
      }
    } else {
      try {
        map.get(null);
      } catch (NullPointerException optional) {
      }
    }

   * that use {@code comparator} to determine the least and greatest elements.
   */
  /*
   * TODO(cpovirk): Change to Comparator<? super B> to permit Comparator<@Nullable ...> and
   * Comparator<SupertypeOfB>? What we have here matches the immutable collections, but those also
   * expose a public Builder constructor that accepts "? super." So maybe we should do *that*
   * instead.
   */

      ExampleStackTrace path = acquiredLock.findPathTo(this, seen);

      if (path == null) {
        // this can be safely acquired after the acquiredLock.
        //
        // Note that there is a race condition here which can result in missing
        // a cyclic edge: it's possible for two threads to simultaneous find
        // "safe" edges which together form a cycle. Preventing this race

  private static <E extends @Nullable Object> boolean addAllImpl(
      Multiset<E> self, Multiset<? extends E> elements) {
    // It'd be nice if we could specialize for ImmutableMultiset here without also retaining
    // its code when it's not in scope...
    if (elements instanceof AbstractMapBasedMultiset) {
      return addAllImpl(self, (AbstractMapBasedMultiset<? extends E>) elements);

    // exchanging two blocks of memory). This classic text by Gries and Mills mentions several:
    // https://ecommons.cornell.edu/bitstream/handle/1813/6292/81-452.pdf.
    // (1) "Reversal", the one we have here.
    // (2) "Dolphin". If we're rotating an array a of size n by a distance of d, then element a[0]
    //     ends up at a[d], which in turn ends up at a[2d], and so on until we get back to a[0].

    ImmutableSet<Integer> elements = ImmutableSet.of(1, 2, 3);
    Set<Set<Integer>> powerSet = powerSet(elements);
    // The API doesn't promise this iteration order, but it's convenient here.
    Iterator<Set<Integer>> i = powerSet.iterator();
    assertEquals(ImmutableSet.of(), i.next());
    assertEquals(ImmutableSet.of(1), i.next());
    assertEquals(ImmutableSet.of(2), i.next());

      // will be resized. That threshold is ceilingPowerOfTwo(capacity*loadFactor), where
      // loadFactor is 0.75 by default. So with the calculation here we ensure that the
      // threshold is equal to ceilingPowerOfTwo(expectedSize). There is a separate code
      // path when the first operation on the new map is putAll(otherMap). There, prior to

      // will be resized. That threshold is ceilingPowerOfTwo(capacity*loadFactor), where
      // loadFactor is 0.75 by default. So with the calculation here we ensure that the
      // threshold is equal to ceilingPowerOfTwo(expectedSize). There is a separate code
      // path when the first operation on the new map is putAll(otherMap). There, prior to

public class EnumsBenchmark {

  @Param({"Small", "Medium", "Large"})
  String enumSize;

  @Param({"0.2", "0.8"})
  float hitRate;

  // We could avoid the raw type here by initializing this with a ternary (? SmallEnum.class : ...).
  // However, we end up needing a raw type in getIfPresent, as discussed there.
  @SuppressWarnings("rawtypes")
  private Class<? extends Enum> enumType;