*
 * @author Jared Levy
 * @since 2.0
 */
@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

@GwtCompatible
abstract class CommonPattern {
  public abstract CommonMatcher matcher(CharSequence t);

  public abstract String pattern();

  public abstract int flags();

  // Re-declare this as abstract to force subclasses to override.
  @Override
  public abstract String toString();

  public static CommonPattern compile(String pattern) {
    return Platform.compilePattern(pattern);
  }

  public static boolean isPcreLike() {

/**
 * Base class for implementing services that can handle {@link #doStart} and {@link #doStop}
 * requests, responding to them with {@link #notifyStarted()} and {@link #notifyStopped()}
 * callbacks. Its subclasses must manage threads manually; consider {@link
 * AbstractExecutionThreadService} if you need only a single execution thread.
 *
 * @author Jesse Wilson
 * @author Luke Sandberg
 * @since 1.0
 */
@GwtIncompatible

        default:
            return "Unknown error: 0x" + Integer.toHexString(returnCode);
        }
    }

    /**
     * Encodes the witness RPC message parameters to NDR format.
     * Subclasses must implement this method to encode their specific parameters.
     *
     * @param buf the NDR buffer to encode into
     * @throws NdrException if encoding fails
     */

   * situations, you may wish to override {@link ForwardingMultiset#elementSet} to forward to this
   * implementation or a subclass thereof.
   *
   * @since 10.0
   */
  protected class StandardElementSet extends Multisets.ElementSet<E> {
    /** Constructor for use by subclasses. */
    public StandardElementSet() {}

    @Override
    Multiset<E> multiset() {
      return ForwardingMultiset.this;
    }

 * @author Sven Mawson
 * @since 15.0
 */
@GwtCompatible
@SuppressWarnings("EscapedEntity") // We do mean for the user to see "<" etc.
public abstract class CharEscaper extends Escaper {
  /** Constructor for use by subclasses. */
  protected CharEscaper() {}

  /**
   * Returns the escaped form of a given literal string.
   *
   * @param string the literal string to be escaped
   * @return the escaped form of {@code string}

import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.SortedSet;
import org.jspecify.annotations.Nullable;

/**
 * A sorted set which forwards all its method calls to another sorted set. Subclasses should
 * override one or more methods to modify the behavior of the backing sorted set as desired per the
 * <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *

 *
 * <p>This class implements all methods in {@code ListenableFuture}. Subclasses should provide a way
 * to set the result of the computation through the protected methods {@link #set(Object)}, {@link
 * #setFuture(ListenableFuture)} and {@link #setException(Throwable)}. Subclasses may also override
 * {@link #afterDone()}, which will be invoked automatically when the future completes. Subclasses
 * should rarely override other methods.
 *
 * @author Sven Mawson

 *
 * <p>Subclasses are guaranteed that the life cycle methods ({@link #runOneIteration}, {@link
 * #startUp} and {@link #shutDown}) will never run concurrently. Notably, if any execution of {@link
 * #runOneIteration} takes longer than its schedule defines, then subsequent executions may start
 * late. Also, all life cycle methods are executed with a lock held, so subclasses can safely modify

import sun.misc.Unsafe;

/**
 * A package-local class holding common representation and mechanics for classes supporting dynamic
 * striping on 64bit values. The class extends Number so that concrete subclasses must publicly do
 * so.
 */
@GwtIncompatible
@SuppressWarnings("SunApi") // b/345822163
abstract class Striped64 extends Number {
  /*
   * This class maintains a lazily-initialized table of atomically