chains().of(stream -> stream.forEach(c -> c.delete(user)));
    }

    public User load(final User user) {
        User u = user;
        for (final AuthenticationChain chain : chains) {
            u = chain.load(u);
        }
        return u;
    }

    public void addChain(final AuthenticationChain chain) {
        chains = ArrayUtils.addAll(chains, chain);
    }

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

/**
 * MapMaker emulation.
 *
 * @author Charles Fry
 */
@ElementTypesAreNonnullByDefault
public final class MapMaker {
  private int initialCapacity = 16;

  public MapMaker() {}

  @CanIgnoreReturnValue

   * of common.collect a second time with the results of the first compilation on the classpath. Or
   * just back this out once we stop doing that (which we'll do after our internal GWT setup
   * changes).
   */
  @Override
  public ImmutableMap<Object, Collection<Object>> asMap() {
    return super.asMap();
  }

  private Object readResolve() {
    return INSTANCE; // preserve singleton property
  }

      allowedOnPath = ".*/com/google/common/base/.*")
  CommonPattern compile(String pattern);

  /**
   * Returns {@code true} if the regex implementation behaves like Perl -- notably, by supporting
   * possessive quantifiers but also being susceptible to catastrophic backtracking.
   */
  @RestrictedApi(

import com.google.common.testing.NullPointerTester;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CountDownLatch;
import junit.framework.TestCase;

/**
 * @author Charles Fry
 */
@GwtCompatible(emulated = true)
@J2ktIncompatible // MapMaker
public class MapMakerTest extends TestCase {
  @GwtIncompatible // NullPointerTester
  public void testNullParameters() throws Exception {

 * in terms of {@link #invalidate}. The method {@link #cleanUp} is a no-op. All other methods throw
 * an {@link UnsupportedOperationException}.
 *
 * @author Charles Fry
 * @since 11.0
 */
@GwtIncompatible
@ElementTypesAreNonnullByDefault
public abstract class AbstractLoadingCache<K, V> extends AbstractCache<K, V>
    implements LoadingCache<K, V> {

 * in terms of {@link #invalidate}. The method {@link #cleanUp} is a no-op. All other methods throw
 * an {@link UnsupportedOperationException}.
 *
 * @author Charles Fry
 * @since 11.0
 */
@GwtIncompatible
@ElementTypesAreNonnullByDefault
public abstract class AbstractLoadingCache<K, V> extends AbstractCache<K, V>
    implements LoadingCache<K, V> {

 *
 * <p>Note that {@link #get}, {@link #getUnchecked}, and {@link #apply} all expose the same
 * underlying functionality, so should probably be overridden as a group.
 *
 * @author Charles Fry
 * @since 11.0
 */
@GwtIncompatible
@ElementTypesAreNonnullByDefault
public abstract class ForwardingLoadingCache<K, V> extends ForwardingCache<K, V>
    implements LoadingCache<K, V> {

import java.util.concurrent.atomic.AtomicReference;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit test for {@link AbstractLoadingCache}.
 *
 * @author Charles Fry
 */
public class AbstractLoadingCacheTest extends TestCase {

  public void testGetUnchecked_checked() {
    final Exception cause = new Exception();

   * first permutation will be in ascending order, and the last will be in descending order.
   *
   * <p>Duplicate elements are considered equal. For example, the list [1, 1] will have only one
   * permutation, instead of two. This is why the elements have to implement {@link Comparable}.
   *
   * <p>An empty iterable has only one permutation, which is an empty list.
   *