worked everywhere that I know of except for one place: when running the GWT
    util.concurrent tests under Guava.

    The problem is that GWT responds poorly to two .gwt.xml files in the same
    Java package; see https://goo.gl/pRV3Yn 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.annotations.GwtIncompatible;
import java.time.Duration;
import java.util.EnumSet;
import java.util.concurrent.Callable;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**

 */

package com.google.common.util.concurrent;

import static com.google.common.util.concurrent.Futures.getUnchecked;
import static com.google.common.util.concurrent.Futures.immediateFuture;
import static com.google.common.util.concurrent.FuturesGetCheckedInputs.CHECKED_EXCEPTION;
import static com.google.common.util.concurrent.FuturesGetCheckedInputs.ERROR;
import static com.google.common.util.concurrent.FuturesGetCheckedInputs.ERROR_FUTURE;

import com.google.common.util.concurrent.ClosingFuture.ClosingCallable;
import com.google.common.util.concurrent.ClosingFuture.DeferredCloser;
import com.google.common.util.concurrent.ClosingFuture.ValueAndCloser;
import com.google.common.util.concurrent.ClosingFuture.ValueAndCloserConsumer;
import java.io.Closeable;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;

 */

package com.google.common.util.concurrent;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.collect.Lists.newArrayList;
import static com.google.common.util.concurrent.Futures.immediateFailedFuture;
import static com.google.common.util.concurrent.Futures.immediateFuture;
import static com.google.common.util.concurrent.FuturesGetChecked.checkExceptionClassValidity;

import com.google.common.util.concurrent.ListeningScheduledExecutorService;
import com.google.common.util.concurrent.MoreExecutors;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.Delayed;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;

 */

package com.google.common.util.concurrent;

import static com.google.common.util.concurrent.Futures.getUnchecked;
import static com.google.common.util.concurrent.Futures.immediateFuture;
import static com.google.common.util.concurrent.FuturesGetCheckedInputs.CHECKED_EXCEPTION;
import static com.google.common.util.concurrent.FuturesGetCheckedInputs.ERROR;
import static com.google.common.util.concurrent.FuturesGetCheckedInputs.ERROR_FUTURE;

FIELD com.google.common.util.concurrent.AbstractFuture.Listener.executor com.google.common.util.concurrent.MoreExecutors.rejectionPropagatingExecutor.$
FIELD com.google.common.util.concurrent.AbstractService.listeners
# NonReentrantExecutor is not exposed to this field
FIELD com.google.common.util.concurrent.ExecutionSequencer.ThreadConfinedTaskQueue.nextExecutor com.google.common.util.concurrent.ExecutionSequencer.TaskNonReentrantExecutor

import com.google.common.testing.TearDownStack;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import junit.framework.TestCase;

import com.google.common.util.concurrent.ListeningExecutorService;
import com.google.common.util.concurrent.ListeningScheduledExecutorService;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.AbstractExecutorService;
import java.util.concurrent.Callable;
import java.util.concurrent.Delayed;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;