util.concurrent tests under Guava.

    The problem is that GWT responds poorly to two .gwt.xml files in the same
    Java package; see
    https://groups.google.com/g/google-web-toolkit-contributors/c/CqYH59Dt_rQ/m/uVGW1QdUsXUJ
    for details.

    The summary is that it ignores one file in favor of the other.
    util.concurrent, like nearly all our packages, has two .gwt.xml files: one

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Queues;
import com.google.common.util.concurrent.Uninterruptibles;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.CyclicBarrier;
import junit.framework.TestCase;

/**
 * Tests for {@link Dispatcher} implementations.
 *
 * @author Colin Decker
 */

import java.nio.charset.UnsupportedCharsetException;
import java.util.ConcurrentModificationException;
import java.util.NoSuchElementException;
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;

import java.nio.charset.UnsupportedCharsetException;
import java.util.ConcurrentModificationException;
import java.util.NoSuchElementException;
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;

import static com.google.common.util.concurrent.Internal.toNanosSaturated;
import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
import static com.google.common.util.concurrent.Service.State.FAILED;
import static com.google.common.util.concurrent.Service.State.NEW;
import static com.google.common.util.concurrent.Service.State.RUNNING;
import static com.google.common.util.concurrent.Service.State.STARTING;

import static com.google.common.util.concurrent.Internal.toNanosSaturated;
import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
import static com.google.common.util.concurrent.Service.State.FAILED;
import static com.google.common.util.concurrent.Service.State.NEW;
import static com.google.common.util.concurrent.Service.State.RUNNING;
import static com.google.common.util.concurrent.Service.State.STARTING;

import static org.junit.Assert.assertThrows;

import com.google.common.testing.GcFinalization.FinalizationPredicate;
import com.google.common.util.concurrent.SettableFuture;
import java.lang.ref.WeakReference;
import java.util.WeakHashMap;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicBoolean;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.lang.Thread.UncaughtExceptionHandler;
import java.util.Locale;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicLong;
import javax.annotation.CheckForNull;

/**
 * A ThreadFactory builder, providing any combination of these features:
 *
 * <ul>

 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.util.concurrent;

import com.google.common.annotations.GwtCompatible;
import java.util.concurrent.ScheduledFuture;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Helper interface to implement both {@link ListenableFuture} and {@link ScheduledFuture}.
 *

import com.google.common.base.Function;
import com.google.common.collect.ImmutableMap;
import com.google.common.util.concurrent.ExecutionError;
import com.google.common.util.concurrent.UncheckedExecutionException;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutionException;

/**