* that use non-standard notions of key equality, such as the entry of a {@code SortedMap} whose
 * comparator is not consistent with {@code equals}.
 *
 * <p>The {@code standard} methods are not guaranteed to be thread-safe, even when all of the
 * methods that they depend on are thread-safe.
 *
 * @author Mike Bostock
 * @author Louis Wasserman
 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault

 * standard JDK exceptions such as {@link java.util.NoSuchElementException} or {@link
 * UnsupportedOperationException} in the situations they are intended for.
 *
 * <h3>Non-preconditions</h3>
 *
 * <p>It is of course possible to use the methods of this class to check for invalid conditions
 * which are <i>not the caller's fault</i>. Doing so is <b>not recommended</b> because it is
 * misleading to future readers of the code and of stack traces. See <a

 * <p><b>Java 8+ users:</b> several common uses for this class are now more comprehensively
 * addressed by the new {@link java.util.stream.Stream} library. Read the method documentation below
 * for comparisons. This class is not being deprecated, but we gently encourage you to migrate to
 * streams.
 *
 * <p><i>Performance notes:</i> Unless otherwise noted, all of the iterables produced in this class

      if (entry instanceof ImmutableEntry) {
        checkNotNull(entry.getKey());
        checkNotNull(entry.getValue());
        @SuppressWarnings("unchecked") // all supported methods are covariant
        Entry<K, V> immutableEntry = (Entry<K, V>) entry;
        entries.add(immutableEntry);
      } else {
        entries.add(entryOf((K) entry.getKey(), (V) entry.getValue()));
      }

   *       underlying contents.
   *   <li>All methods that return objects that can indirectly mutate the collection throw
   *       UnsupportedOperationException when those mutators are called.
   * </ol>
   *
   * @param collection the presumed-immutable collection
   * @param sampleElement an element of the same type as that contained by {@code collection}.

@GwtCompatible
public enum MultisetFeature implements Feature<Multiset> {
  /**
   * Indicates that elements from {@code Multiset.entrySet()} update to reflect changes in the
   * backing multiset.
   */
  ENTRIES_ARE_VIEWS;

  @Override
  public Set<Feature<? super Multiset>> getImpliedFeatures() {
    return Collections.emptySet();
  }

  @Retention(RetentionPolicy.RUNTIME)
  @Inherited
  @TesterAnnotation

   *
   * <p>Despite the method name, this method attempts to avoid actually copying the data when it is
   * safe to do so. The exact circumstances under which a copy will or will not be performed are
   * undocumented and subject to change.
   *
   * <p>Note that if {@code list} is a {@code List<String>}, then {@code ImmutableList.copyOf(list)}

   *
   * <p>This method always throws an exception. The {@code RuntimeException} return type allows
   * client code to signal to the compiler that statements after the call are unreachable. Example
   * usage:
   *
   * <pre>
   * T doSomething() {
   *   try {
   *     return someMethodThatCouldThrowAnything();
   *   } catch (IKnowWhatToDoWithThisException e) {

    return CollectCollectors.toImmutableMultiset(Function.identity(), e -> 1);
  }

  /**
   * Returns a {@code Collector} that accumulates elements into an {@code ImmutableMultiset} whose
   * elements are the result of applying {@code elementFunction} to the inputs, with counts equal to
   * the result of applying {@code countFunction} to the inputs.
   *

   *
   * <p>This method always throws an exception. The {@code RuntimeException} return type allows
   * client code to signal to the compiler that statements after the call are unreachable. Example
   * usage:
   *
   * <pre>
   * T doSomething() {
   *   try {
   *     return someMethodThatCouldThrowAnything();
   *   } catch (IKnowWhatToDoWithThisException e) {