@ElementTypesAreNonnullByDefault
public class ExecutionError extends Error {
  /*
   * Ideally, this class would have exposed only constructors that require a non-null cause. See
   * https://github.com/jspecify/jspecify-reference-checker/blob/61aafa4ae52594830cfc2d61c8b113009dbdb045/src/main/java/com/google/jspecify/nullness/NullSpecTransfer.java#L789
   * and https://github.com/jspecify/jspecify/issues/490.
   *

import com.google.common.annotations.GwtCompatible;
import java.util.Collection;
import java.util.Set;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A set which forwards all its method calls to another set. Subclasses should override one or more
 * methods to modify the behavior of the backing set as desired per the <a

import java.security.Permission;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit tests for {@link Callables}.
 *
 * @author Isaac Shum
 */
@GwtCompatible(emulated = true)
public class CallablesTest extends TestCase {

import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Objects;
import com.google.common.primitives.Ints;
import java.util.Arrays;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Helper classes and static methods for implementing compact hash-based collections.
 *
 * @author Jon Noack
 */
@GwtIncompatible
@ElementTypesAreNonnullByDefault

import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Abstract test case parent for anything implementing {@link ListenableFuture}. Tests the two get
 * methods and the addListener method.
 *
 * @author Sven Mawson
 * @since 10.0
 */

import java.util.Collection;
import java.util.Map;
import java.util.NavigableSet;
import java.util.SortedSet;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Basic implementation of the {@link SortedSetMultimap} interface. It's a wrapper around {@link
 * AbstractMapBasedMultimap} that converts the returned collections into sorted sets. The {@link

import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Implementation of {@link Multimaps#filterKeys(Multimap, Predicate)}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault

import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeoutException;
import junit.framework.AssertionFailedError;
import org.checkerframework.checker.nullness.qual.Nullable;

/** Replacements for JUnit's {@code assertThrows} that work under GWT/J2CL. */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
final class ReflectionFreeAssertThrows {

import java.io.OutputStream;
import java.net.URL;
import java.util.HashSet;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Base test case class for I/O tests.
 *
 * @author Chris Nokleberg
 * @author Colin Decker
 */
public abstract class IoTestCase extends TestCase {

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

/** Test case for {@link TrustedListenableFutureTask}. */
@ElementTypesAreNonnullByDefault
@GwtCompatible(emulated = true)
public class TrustedListenableFutureTaskTest extends TestCase {