if (node.previousSibling == null) {
        // requireNonNull is safe because we checked that not *both* siblings were null.
        keyList.head = requireNonNull(node.nextSibling);
      } else {
        node.previousSibling.nextSibling = node.nextSibling;
      }

      if (node.nextSibling == null) {
        // requireNonNull is safe because we checked that not *both* siblings were null.

import java.util.NoSuchElementException;
import java.util.Set;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutionException;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * LocalCache emulation for GWT.
 *
 * @param <K> the base key type
 * @param <V> the base value type
 * @author Charles Fry
 * @author Jon Donovan
 */

import java.util.concurrent.Future;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.checkerframework.checker.nullness.qual.Nullable;
import sun.misc.Unsafe;

/** Benchmarks for {@link ExecutionList}. */
@VmOptions({"-Xms8g", "-Xmx8g"})
public class ExecutionListBenchmark {

import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.SortedSet;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Collection tests for {@link Table} implementations.
 *
 * @author Jared Levy
 * @author Louis Wasserman
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault

import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Locale;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit test for {@link Chars}.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public class CharsTest extends TestCase {

import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.TypeVariable;
import java.util.Collections;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit tests for {@link Invokable}.
 *
 * @author Ben Yu
 */
@AndroidIncompatible // lots of failures, possibly some related to bad equals() implementations?

import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.SortedSet;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Collection tests for {@link Table} implementations.
 *
 * @author Jared Levy
 * @author Louis Wasserman
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault

import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.TypeVariable;
import java.util.Collections;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit tests for {@link Invokable}.
 *
 * @author Ben Yu
 */
@AndroidIncompatible // lots of failures, possibly some related to bad equals() implementations?

import java.util.concurrent.Callable;
import java.util.concurrent.Executor;
import java.util.concurrent.atomic.AtomicReference;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Serializes execution of tasks, somewhat like an "asynchronous {@code synchronized} block." Each
 * {@linkplain #submit enqueued} callable will not be submitted to its associated executor until the

import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.Random;
import java.util.RandomAccess;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.NonNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit tests for {@code Ordering}.
 *
 * @author Jesse Wilson
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault