*
 * @author Louis Wasserman
 */
@GwtCompatible
abstract class TransformedIterator<F extends @Nullable Object, T extends @Nullable Object>
    implements Iterator<T> {
  final Iterator<? extends F> backingIterator;

  TransformedIterator(Iterator<? extends F> backingIterator) {
    this.backingIterator = checkNotNull(backingIterator);
  }

  @ParametricNullness

import static java.util.Objects.requireNonNull;

/**
 * Base class for requests.
 *
 * @since 4.0.0
 */
@Experimental
abstract class BaseRequest<S extends ProtoSession> implements Request<S> {

    private final S session;
    private final RequestTrace trace;

    protected BaseRequest(@Nonnull S session) {
        this(session, null);
    }

    private static final byte[] ZERO_IV = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

    /**
     * Calculates a MAC using the ARCFOUR-HMAC-MD5 algorithm.
     * This method implements the Microsoft variant of the Kerberos ARCFOUR-HMAC-MD5 checksum.
     *
     * @param keyusage the Kerberos key usage number for this operation
     * @param key the encryption key to use for MAC calculation

          return new SimpleStatsCounter();
        }
      };

  enum NullListener implements RemovalListener<Object, Object> {
    INSTANCE;

    @Override
    public void onRemoval(RemovalNotification<Object, Object> notification) {}
  }

  enum OneWeigher implements Weigher<Object, Object> {
    INSTANCE;

    @Override
    public int weigh(Object key, Object value) {

 * Negotiation Protocol) authentication. It contains the username extracted from the
 * SPNEGO authentication process, typically from a Kerberos ticket.
 */
public class SpnegoCredential implements LoginCredential, FessCredential {

    /** The username extracted from SPNEGO authentication. */
    private final String username;

    /**
     * Constructs a new SpnegoCredential with the specified username.

 *
 * @author George van den Driessche
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible
public enum ListFeature implements Feature<List> {
  SUPPORTS_SET,
  SUPPORTS_ADD_WITH_INDEX(CollectionFeature.SUPPORTS_ADD),
  SUPPORTS_REMOVE_WITH_INDEX(CollectionFeature.SUPPORTS_REMOVE),

  GENERAL_PURPOSE(
      CollectionFeature.GENERAL_PURPOSE,

import org.jspecify.annotations.NullUnmarked;

/**
 * A byte sink for testing that has configurable behavior.
 *
 * @author Colin Decker
 */
@NullUnmarked
public class TestByteSink extends ByteSink implements TestStreamSupplier {

  private final ByteArrayOutputStream bytes = new ByteArrayOutputStream();
  private final ImmutableSet<TestOption> options;

  private boolean outputStreamOpened;

 * Optional features of classes derived from {@code Multimap}.
 *
 * @author Louis Wasserman
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible
public enum MultimapFeature implements Feature<Multimap> {
  VALUE_COLLECTIONS_SUPPORT_ITERATOR_REMOVE;

  private final Set<Feature<? super Multimap>> implied;

  MultimapFeature(Feature<? super Multimap>... implied) {
    this.implied = copyToSet(implied);

            }
          };
    }
    SUPPLIER = supplier;
  }

  public static LongAddable create() {
    return SUPPLIER.get();
  }

  private static final class PureJavaLongAddable extends AtomicLong implements LongAddable {
    @Override
    public void increment() {
      getAndIncrement();
    }

    @Override
    public void add(long x) {
      getAndAdd(x);
    }

    @Override

 *
 * @since 7.0
 * @author Louis Wasserman
 */
@GwtCompatible
public abstract class UnmodifiableListIterator<E extends @Nullable Object>
    extends UnmodifiableIterator<E> implements ListIterator<E> {
  /** Constructor for use by subclasses. */
  protected UnmodifiableListIterator() {}

  /**
   * Guaranteed to throw an exception and leave the underlying data unmodified.
   *