*
   * @see java.util.Collection the definition of general-purpose collections.
   */
  GENERAL_PURPOSE(SUPPORTS_ADD, SUPPORTS_REMOVE, SUPPORTS_ITERATOR_REMOVE),

  /** Features supported by collections where only removal is allowed. */
  REMOVE_OPERATIONS(SUPPORTS_REMOVE, SUPPORTS_ITERATOR_REMOVE),

  SERIALIZABLE,
  SERIALIZABLE_INCLUDING_VIEWS(SERIALIZABLE),

  SUBSET_VIEW,
  DESCENDING_VIEW,

  /**

    long blah = 0;
    for (int i = 0; i < reps; i++) {
      Integer key = keys.get(random.nextInt(nKeys));
      // This range is [-5, 4] - slight negative bias so we often hit zero, which brings the
      // auto-removal of zeroes into play.
      int delta = random.nextInt(10) - 5;
      blah += delta;
      if (delta >= 0) {
        multiset.add(key, delta);
      } else {
        multiset.remove(key, -delta);
      }

  /**
   * Returns a map view that associates each key with the corresponding values in the multimap.
   * Changes to the returned map, such as element removal, will update the underlying multimap. The
   * map does not support {@code setValue()} on its entries, {@code put}, or {@code putAll}.
   *

   * Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. Replace with a simple call
   * to Unsafe.getUnsafe when integrating into a jdk.
   *
   * @return a sun.misc.Unsafe
   */
  @SuppressWarnings("removal") // b/318391980
  private static sun.misc.Unsafe getUnsafe() {
    try {
      return sun.misc.Unsafe.getUnsafe();
    } catch (SecurityException tryReflectionInstead) {
    }
    try {

      this.fromList = checkNotNull(fromList);
      this.function = checkNotNull(function);
    }

    /**
     * The default implementation inherited is based on iteration and removal of each element which
     * can be overkill. That's why we forward this call directly to the backing list.
     */
    @Override
    protected void removeRange(int fromIndex, int toIndex) {

   * higher than performing just the operation without enforcing the capacity constraint.
   *
   * This implementation uses a per-segment queue to record a memento of the additions, removals,
   * and accesses that were performed on the map. The queue is drained on writes and when it exceeds
   * its capacity threshold.
   *

   *
   * <p>Static initialization of this class will fail if the {@link sun.misc.Unsafe} object cannot
   * be accessed.
   */
  @SuppressWarnings({"sunapi", "removal"}) // b/318391980
  private static final class UnsafeAtomicHelper extends AtomicHelper {
    static final sun.misc.Unsafe UNSAFE;
    static final long LISTENERS_OFFSET;
    static final long WAITERS_OFFSET;

    valueRef.setLoading(true);
    entry.setValueReference(valueRef);
    table.set(index, entry);
    assertNull(segment.refresh(key, hash, identityLoader(), false));
  }

  // Removal listener tests

  public void testRemovalListener_explicit() {
    QueuingRemovalListener<Object, Object> listener = queuingRemovalListener();

    valueRef.setLoading(true);
    entry.setValueReference(valueRef);
    table.set(index, entry);
    assertNull(segment.refresh(key, hash, identityLoader(), false));
  }

  // Removal listener tests

  public void testRemovalListener_explicit() {
    QueuingRemovalListener<Object, Object> listener = queuingRemovalListener();

 * average, in the marking phase, not {@code 5.0} as in {@code java.util.HashSet}.
 *
 * <p>If there are no removals, then {@link #iterator iteration} order is the same as insertion
 * order. Any removal invalidates any ordering guarantees.
 *
 * <p>This class should not be assumed to be universally superior to {@code java.util.HashSet}.