* Iterator} is a "weakly consistent" iterator that will never throw {@link
   * ConcurrentModificationException}, and guarantees to traverse elements as they existed upon
   * construction of the iterator, and may (but is not guaranteed to) reflect any modifications
   * subsequent to construction.
   *
   * @return an iterator over the elements in this queue in proper sequence
   */

 */
@GwtCompatible
public abstract class UnmodifiableIterator<E extends @Nullable Object> implements Iterator<E> {
  /** Constructor for use by subclasses. */
  protected UnmodifiableIterator() {}

  /**
   * Guaranteed to throw an exception and leave the underlying data unmodified.
   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @Deprecated
  @Override

/**
 * Signifies that a public API (public class, method or field) is subject to incompatible changes,
 * or even removal, in a future release. An API bearing this annotation is exempt from any
 * compatibility guarantees made by its containing library. Note that the presence of this
 * annotation implies nothing about the quality or performance of the API in question, only the fact
 * that it is not "API-frozen."
 *

/**
 * Signifies that a public API (public class, method or field) is subject to incompatible changes,
 * or even removal, in a future release. An API bearing this annotation is exempt from any
 * compatibility guarantees made by its containing library. Note that the presence of this
 * annotation implies nothing about the quality or performance of the API in question, only the fact
 * that it is not "API-frozen."
 *

     * Execution is the execution of the phase proper. Failure of any {@code #AT} dynamic phase execution will fail
     * the phase. Any {@link #AFTER} phases will still be executed.
     */
    AT(""),
    /**
     * Guaranteed execution dynamic phases on completion of the static phase. All {@code #AFTER} dynamic phases will
     * be executed provided at least one {@link #BEFORE} or {@link #AT} dynamic phase has started execution.
     */

   * complete} or, if the computation is already complete, immediately.
   *
   * <p>There is no guaranteed ordering of execution of listeners, but any listener added through
   * this method is guaranteed to be called once the computation is complete.
   *
   * <p>Exceptions thrown by a listener will be propagated up to the executor. Any exception thrown

   *   <li>We could make {@link #countMap} no longer be {@code final}. Then we could write to it
   *       directly during deserialization. However, we would lose Java's guarantees for {@code
   *       final} fields, including that their values are guaranteed to be visible even when an
   *       instance is unsafely published.
   * </ul>
   */
  private transient @Nullable ConcurrentHashMultiset<E> deserializationReplacement;

   * already been re-added.
   */
  // Technically should accept RemovalNotification<? extends K, ? extends V>, but because
  // RemovalNotification is guaranteed covariant, let's make users' lives simpler.
  void onRemoval(RemovalNotification<K, V> notification);

 */
@J2ktIncompatible
@GwtIncompatible
@J2ObjCIncompatible // java.nio.file
public enum RecursiveDeleteOption {
  /**
   * Specifies that the recursive delete should not throw an exception when it can't be guaranteed
   * that it can be done securely, without vulnerability to race conditions (i.e. when the file
   * system does not support {@link SecureDirectoryStream}).
   *

   * complete} or, if the computation is already complete, immediately.
   *
   * <p>There is no guaranteed ordering of execution of listeners, but any listener added through
   * this method is guaranteed to be called once the computation is complete.
   *
   * <p>Exceptions thrown by a listener will be propagated up to the executor. Any exception thrown